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Metallic Materials: Microstructure, Phase Equilibria and Thermodynamics

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Metals and Alloys".

Deadline for manuscript submissions: 31 July 2024 | Viewed by 12123

Special Issue Editors

State Key Laboratory of Powder Metallurgy, Central South University, Changsha, China
Interests: phase equilibria; thermodynamics; diffusion kinetics; simulation of microstructure evolution

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Guest Editor
State Key Laboratory of Powder Metallurgy, Central South University, Changsha, China
Interests: metal matrix composites; thermodynamics; superalloys

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Guest Editor
State Key Laboratory of Powder Metallurgy, Central South University, Changsha, China
Interests: phase diagram thermodynamics; diffusion and interface reaction; material measurement and calculation simulation; material microstructure evolution simulation

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Guest Editor
School of Materials Science and Engineering, Shanghai University, Shanghai, China
Interests: thermodynamics; phase transformation; kinetics; magnesium alloys

Special Issue Information

Dear Colleagues,

Thermodynamics describes the state of a system and its interaction with its surroundings, which is an extremely powerful tool in the field of materials science. The first law of thermodynamics, which describes the conservation of energy; the second law, which describes the principle of entropy increase; and the third law, which describes the inability to reach absolute zero, form the core theory of thermodynamics. The study of thermodynamics is central to the understanding of phase equilibria and phase transformation, which helps to construct relationships between composition, microstructure, processes and properties.

The relationship between thermodynamic functions and the equilibrium phase diagram of a binary system was made explicit as early as 1908. As computers continued to improve, Kaufmann proposed lattice stability in 1970, the seminal work of CALculation of PHAse Diagram (CALPHAD). After more than 50 years of development in engineering design and computational simulation, a particularly successful and widely used modeling method in thermodynamics is the CALPHAD method. This method can now be used to predict phase equilibria, phase diagram and various thermophysical parameters, which are key inputs for microstructure simulation and performance prediction.

Microstructure, phase equilibria and thermodynamics are the basis for integrated computational materials engineering and need to be studied systematically and in depth.

In light of the above, I wish to invite you to submit a manuscript for this Special Issue. Full papers, communications, and reviews are all welcome.

Dr. Yuling Liu
Dr. Peisheng Wang
Prof. Dr. Yong Du
Prof. Dr. Qun Luo
Guest Editors

Manuscript Submission Information

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Keywords

  • phase diagram
  • CALPHAD
  • thermodynamics
  • microstructure
  • materials design
  • phase transformation

Published Papers (14 papers)

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Research

13 pages, 4055 KiB  
Article
The Fabrication of Ultrahigh-Strength Steel with a Nanolath Structure via Quenching–Partitioning–Tempering
by Wenting Xu, Li Xie, Xiaoying Liu, Jiangnan Wang, Yuxuan Xu, Mingtao He, Kejun Hu, Chang Liu and Wei Yu
Materials 2024, 17(5), 1161; https://doi.org/10.3390/ma17051161 - 01 Mar 2024
Viewed by 600
Abstract
A novel low-alloy ultrahigh-strength steel featuring excellent mechanical properties and comprising a nanolath structure was fabricated in this work using a quenching–partitioning–tempering (Q-P-T) process. The Q-P-T process comprised direct quenching and an isothermal bainitic transformation for partitioning after thermo-mechanical control processing (online Q&P) [...] Read more.
A novel low-alloy ultrahigh-strength steel featuring excellent mechanical properties and comprising a nanolath structure was fabricated in this work using a quenching–partitioning–tempering (Q-P-T) process. The Q-P-T process comprised direct quenching and an isothermal bainitic transformation for partitioning after thermo-mechanical control processing (online Q&P) and offline tempering (reheating and tempering). The ultrafine nanolath martensite/bainite mixed structure, combined with residual austenite in the form of a thin film between the nanolaths, was formed, thereby conferring excellent mechanical properties to the steel structures. After the Q-P-T process, the yield and tensile strengths of the steels reached 1450 MPa and 1726 MPa, respectively. Furthermore, the Brinell hardness and elongation rate were 543 HB and 11.5%, respectively, with an average impact energy of 20 J at room temperature. Full article
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18 pages, 2343 KiB  
Article
Thermodynamics of Formation and Liquid–Vapor Phase Transitions of Antimony Alloys with Selenium and Sulfur
by Valeriy Volodin, Alina Nitsenko, Sergey Trebukhov, Xeniya Linnik and Yerkebulan Gapurov
Materials 2024, 17(1), 125; https://doi.org/10.3390/ma17010125 - 26 Dec 2023
Viewed by 612
Abstract
The authors conducted liquid solution studies of antimony with selenium and sulfur in order to provide information on the thermodynamic functions of the formation of these alloys. The studies are based on the vapor pressure values of the components, comprising the double partial [...] Read more.
The authors conducted liquid solution studies of antimony with selenium and sulfur in order to provide information on the thermodynamic functions of the formation of these alloys. The studies are based on the vapor pressure values of the components, comprising the double partial systems of antimony with antimony chalcogenides (Sb2Se3 and Sb2S3) and antimony chalcogenides with chalcogens (Se and S). We calculated the thermodynamic functions of mixing (graphical dependencies) and evaporation (tabular data) based on the partial vapor pressure values of components, which are represented by temperature–concentration dependencies. Based on the partial pressure values of melt components, we calculated the boundaries of liquid and vapor coexistence fields at atmospheric pressure (101.3 kPa) and in a vacuum (0.9 kPa). We established the absence of the stratification region on the Sb2S3–S diagram due to the fact that, on state diagrams, the stratification region is indicated at temperatures above 530 °C, while the boiling point of liquid sulfur at an atmospheric pressure corresponds to 429 °C. Based on the position of the field boundaries (L + V) on the state diagrams, the separation of antimony alloys with selenium and sulfur via distillation into elements at atmospheric pressure is difficult due to the high boiling points of antimony-based alloys in a vacuum: Sb2Se3–Se melts require some number of condensate re-evaporation cycles. Full article
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16 pages, 4193 KiB  
Article
A Yield Stress and Work Hardening Model of Al-Mg-Si Alloy Considering the Strengthening Effect of β” and β’ Precipitates
by Xiaoyu Zheng, Qi Huang, Hong Mao, Kai Li, Namin Xiao, Xingwu Li, Yong Du, Yuling Liu and Yi Kong
Materials 2023, 16(22), 7183; https://doi.org/10.3390/ma16227183 - 16 Nov 2023
Viewed by 846
Abstract
Precipitates are the primary source of strength for the Al-Mg-Si alloy. Aluminum alloy in the peak-aged state mainly contains β” and β’ precipitates. Most of the literature has only considered the strengthening effect of β”. Here, we develop a single-crystal intensity model including [...] Read more.
Precipitates are the primary source of strength for the Al-Mg-Si alloy. Aluminum alloy in the peak-aged state mainly contains β” and β’ precipitates. Most of the literature has only considered the strengthening effect of β”. Here, we develop a single-crystal intensity model including both precipitate enhancement effects for the first time. This model was subsequently implemented into a crystal plastic finite-element method to model the uniaxial tensile process of a polycrystalline aggregate model of Al-Mg-Si alloy. The simulation results for uniaxial stretching are in good agreement with the experimental results, confirming that the constitutive parameters used for the single-crystal strength model with two precipitates are based on realistic physical implications. Furthermore, by comparing the uniaxial tensile simulation results of a peak-aged alloy considering the actual precipitated phase composition of the alloy with those assuming that the precipitated phase is only the β” phase, the predicted tensile strength of the former is around 5.65% lower than that of the latter, suggesting that the two kinds of precipitation should be separately considered when simulating the mechanical response of Al-Mg-Si alloy. It is highly expected that the present simulation strategy is not limited to Al-Mg-Si alloys, and it can be equally applied to the other age-enhanced alloys. Full article
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11 pages, 2523 KiB  
Article
The Effect of Lattice Misfits on the Precipitation at Dislocations: Phase-Field Crystal Simulation
by Hong Mao, Changlin Zeng, Zhikang Zhang, Xiong Shuai and Sai Tang
Materials 2023, 16(18), 6307; https://doi.org/10.3390/ma16186307 - 20 Sep 2023
Cited by 1 | Viewed by 897
Abstract
An atomic-scale approach was employed to simulate the formation of precipitates with different lattice misfits in the early stages of the aging of supersaturated aluminum alloys. The simulation results revealed that the increase in lattice misfits could significantly promote the nucleation rate of [...] Read more.
An atomic-scale approach was employed to simulate the formation of precipitates with different lattice misfits in the early stages of the aging of supersaturated aluminum alloys. The simulation results revealed that the increase in lattice misfits could significantly promote the nucleation rate of precipitates, which results in a larger number and smaller size of the precipitates. The morphologies of the precipitates also vary with the degree of a lattice misfit. Moreover, the higher the lattice misfit, the earlier the nucleation of the second phase occurs, which can substantially inhibit the movement of dislocations. The research on the lattice misfit of precipitation can provide theoretical guidance for the design of high-strength aluminum alloys. Full article
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18 pages, 13146 KiB  
Article
Microstructure and Mechanical Behavior of Quaternary Eutectic α+θ+Q+Si Clusters in As-Cast Al-Mg-Si-Cu Alloys
by Kai Li, Yan Yu, Qiang Lu, Yuanfei Li, Qiao Yan, Xinyue Lan, Liya Li, Baishan Chen and Min Song
Materials 2023, 16(18), 6091; https://doi.org/10.3390/ma16186091 - 06 Sep 2023
Viewed by 893
Abstract
Cu additions notably strengthen Al-Mg-Si and Al-Si-Mg alloys due to the dense precipitation of quaternary nano precipitates during ageing. However, the chemical evolution and mechanical behaviors of the quaternary micro-scale Q constituent phase occurring in cast and homogenized states have rarely been studied. [...] Read more.
Cu additions notably strengthen Al-Mg-Si and Al-Si-Mg alloys due to the dense precipitation of quaternary nano precipitates during ageing. However, the chemical evolution and mechanical behaviors of the quaternary micro-scale Q constituent phase occurring in cast and homogenized states have rarely been studied. Meanwhile, there exists a type of AlCuMgSi cluster in the cast state, which has been regarded as Q particles. The accurate identification of phase constituents is the basis for the future design of alloys with better performance. In our work, this type of cluster was revealed to consist of α-Al, θ-Al2Cu, Q, and Si phases through micro-to-atomic scale studies using scanning and transmission electron microscopes. The skeleton of the dendrite was θ phase. The second phases in the dendritic eutectic cluster dissolved quickly during a 4 h homogenization at 550 °C. The Q phase was found to effectively absorb the Fe impurities during casting and homogenization. As a result, the formation of other harmful Fe-rich intermetallics was suppressed. These Q constituent particles were observed to break into separate pieces in an intermediately brittle manner when compressed in situ in a scanning electron microscope. These findings provide insights into the thermodynamic modeling of the Al-Mg-Si-Cu system and alloy design. Full article
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18 pages, 8753 KiB  
Article
Alloying Effect on Transformation Strain and Martensitic Transformation Temperature of Ti-Based Alloys from Ab Initio Calculations
by Honglin Fang, Xingge Xu, Hualei Zhang, Qiaoyan Sun and Jun Sun
Materials 2023, 16(17), 6069; https://doi.org/10.3390/ma16176069 - 04 Sep 2023
Viewed by 695
Abstract
The accurate prediction of alloying effects on the martensitic transition temperature (Ms) is still a big challenge. To investigate the composition-dependent lattice deformation strain and the Ms upon the β to α″ phase transition, we calculate the total [...] Read more.
The accurate prediction of alloying effects on the martensitic transition temperature (Ms) is still a big challenge. To investigate the composition-dependent lattice deformation strain and the Ms upon the β to α″ phase transition, we calculate the total energies and transformation strains for two selected Ti−Nb−Al and Ti−Nb−Ta ternaries employing a first-principles method. The adopted approach accurately estimates the alloying effect on lattice strain and the Ms by comparing it with the available measurements. The largest elongation and the largest compression due to the lattice strain occur along ±[011]β and ±[100]β, respectively. As compared to the overestimation of the Ms from existing empirical relationships, an improved Ms estimation can be realized using our proposed empirical relation by associating the measured Ms with the energy difference between the β and α″ phases. There is a satisfactory agreement between the predicted and measured Ms, implying that the proposed empirical relation could accurately describe the coupling alloying effect on Ms. Both Al and Ta strongly decrease the Ms, which is in line with the available observations. A correlation between the Ms and elastic modulus, C44, is found, implying that elastic moduli may be regarded as a prefactor of composition-dependent Ms. This work sheds deep light on precisely and directly predicting the Ms of Ti-containing alloys from the first-principles method. Full article
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11 pages, 13428 KiB  
Communication
The Fatal Defects in Cast Al-Si Alloys Due to Sn Addition
by Yao Xiao, Jicheng Wang, Qianyu Deng, Li Feng, Dianming Peng, Hui Feng, Kai Li and Yong Du
Materials 2023, 16(17), 6020; https://doi.org/10.3390/ma16176020 - 01 Sep 2023
Viewed by 653
Abstract
Cast defects are common in cast alloys and they are difficult to eliminate without deformation. They strongly degrade the mechanical properties of cast alloys. The addition of some elements can affect the number of cast defects. In this work, the deleterious effect of [...] Read more.
Cast defects are common in cast alloys and they are difficult to eliminate without deformation. They strongly degrade the mechanical properties of cast alloys. The addition of some elements can affect the number of cast defects. In this work, the deleterious effect of Sn addition on the mechanical properties of Al-Si alloys has been investigated via 3D-computed tomography, SEM and TEM. Amorphous Sn oxides were found near the alumina film or formed enclosures with alumina film. The melt containing high Sn content was trapped by enclosures, causing more shrinkage pores during solidification. Cracks likely initiated and expanded along these pores and brittle amorphous Sn oxides, deteriorating the mechanical properties. This work suggests not adding Sn to various Al alloys when used in a cast state. Full article
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11 pages, 5013 KiB  
Article
Effects of Rapid Quenching on Grain Boundary Microstructure and Mechanical Properties of an Al-Mg-Si-Cu Alloy
by Qiao Yan, Yu Qiu, Mingjun Yang, Qiang Lu, Han Lin, Mingbo Yang, Kai Li and Yong Du
Materials 2023, 16(16), 5609; https://doi.org/10.3390/ma16165609 - 13 Aug 2023
Cited by 1 | Viewed by 750
Abstract
Precipitate free zones (PFZs) near grain boundaries generally soften alloys. The quenching rate after solution treatment is an important factor influencing the width of PFZs in Al-Mg-Si-Cu alloy. This study explored the effects of high quenching rates on the grain boundary microstructures and [...] Read more.
Precipitate free zones (PFZs) near grain boundaries generally soften alloys. The quenching rate after solution treatment is an important factor influencing the width of PFZs in Al-Mg-Si-Cu alloy. This study explored the effects of high quenching rates on the grain boundary microstructures and mechanical properties of an Al-Mg-Si-Cu alloy. Samples of various thickness were quenched in water at room temperature and in ethylene glycol at −40 °C, respectively. The results showed that the rapidly quenched samples at −40 °C exhibited better comprehensive mechanical properties than the water-quenched samples. Transmission electron microscopy studies revealed the rapidly quenched samples had wider PFZs, shorter intragranular precipitates, and larger grain boundary precipitates (GBPs) than water-quenched samples. It is proposed that when the quenching rate exceeds the critical cooling rate, e.g., in water quenching or rapid quenching, the formation of PFZs is controlled by the solute depletion mechanism rather than the vacancy depletion mechanism. The nucleation and growth of GBPs thus lead to the depletion of solute atoms, resulting in wider PFZs rather than thinner PFZs according to previous knowledge. This research provides valuable insights into the application of rapid quenching technology for modifying alloys’ microstructures and properties. Full article
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13 pages, 15576 KiB  
Communication
Experimental Investigation of Phase Equilibria of the Ho-Ir-O Ternary System at 1073 K
by Viera Homolová, Lucia Čiripová, Ondřej Zobač, Adéla Zemanová and Ladislav Falat
Materials 2023, 16(15), 5406; https://doi.org/10.3390/ma16155406 - 01 Aug 2023
Viewed by 687
Abstract
An experimental study of the phase equilibria of the Ho-rich part of the Ho-Ir-O ternary system at 1073 K by means of x-ray diffraction, differential scanning calorimetry, and scanning electron microscopy has been carried out. Ho-hcp and four binary compounds, namely Ho3 [...] Read more.
An experimental study of the phase equilibria of the Ho-rich part of the Ho-Ir-O ternary system at 1073 K by means of x-ray diffraction, differential scanning calorimetry, and scanning electron microscopy has been carried out. Ho-hcp and four binary compounds, namely Ho3Ir, Ho5Ir2, Ho5Ir3, and Ho2O3, were identified in the Ho-Ir-O model alloys after long-term annealing (350–1220 h). No solubility of iridium in Ho2O3 oxide and Ho-hcp was observed. No ternary phase was found. Based on the experimental results, an isothermal section of the Ho-rich part of the Ho-Ir-O system at 1073 K was constructed. In addition, the microstructure of as-cast alloys was studied. An irregular eutectic consisting of faceted Ho-phase in Ho3Ir phase was observed in the alloys with Ho-hcp + Ho3Ir + Ho2O3 phase composition, and the temperature of the eutectic reaction Ho-hcp + Ho3Ir ↔ liquid was determined. Full article
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18 pages, 17877 KiB  
Article
Experimental Investigations of Ni–Ti–Ru System: Liquidus Surface Projection and 1150 °C Isothermal Section
by Dupei Ma, Zhi Li, Yan Liu, Manxiu Zhao and Jingxian Hu
Materials 2023, 16(15), 5299; https://doi.org/10.3390/ma16155299 - 27 Jul 2023
Viewed by 778
Abstract
Ruthenium addition inhibits the formation of the topologically close-packed phases in Ni-based superalloys and improves the solid solution strength of Ni–Ti shape memory alloys. Therefore, the Ni–Ti–Ru phase stability is a very valuable indicator of the effects of Ru in Ni-based superalloys and [...] Read more.
Ruthenium addition inhibits the formation of the topologically close-packed phases in Ni-based superalloys and improves the solid solution strength of Ni–Ti shape memory alloys. Therefore, the Ni–Ti–Ru phase stability is a very valuable indicator of the effects of Ru in Ni-based superalloys and Ni–Ti shape memory alloys. In this study, the isothermal section at 1150 °C and liquidus surface projection of the Ni–Ti–Ru ternary system were determined experimentally using the equilibrated alloy method and diffusion couple method, respectively. Alloys were prepared through the arc-melting of Ni, Ti, and Ru (all 99.99% purity), and then vacuum encapsulation in quartz tubes, followed by annealing at 1150 °C for 36 to 1080 h depending on the alloy composition. Diffusion couples were fabricated by joining one single-phase block (τ1) with one two-phase block (Ni3Ti + γ(Ni)), and the couples were annealed under vacuum at 1150 °C for 168 h. Reaction temperatures of as-cast alloys were determined by differential scanning calorimetry performed with heating and cooling rates of 10 °C/min. Scanning electron microscopy and X-ray diffraction were used to analyze the microstructure. Seven three-phase regions were found at the 1150 °C isothermal section. Seven primary solidification regions and five ternary invariant reactions were deduced in the liquidus surface projection. A new ternary compound τ1 was discovered in both the isothermal section at 1150 °C and liquidus surface projection. The results aid in thermodynamic modeling of the system and provide guidance for designing Ni-based superalloys and Ni–Ti shape memory alloys. Full article
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15 pages, 26134 KiB  
Article
Solidification Behavior of Dy-Tb-Fe Alloys through Experimental Study and Thermodynamic Calculation
by Cong Tan, Qi Wei, Weifeng Cheng, Xingyu Liu, Yuchen Bai and Jiang Wang
Materials 2023, 16(13), 4697; https://doi.org/10.3390/ma16134697 - 29 Jun 2023
Viewed by 720
Abstract
In this work, the solidification microstructure and phase transitions of Dy-Tb-Fe alloy samples were studied by using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD) and differential thermal analysis (DTA). No stable ternary compound was detected in the present experiments. [...] Read more.
In this work, the solidification microstructure and phase transitions of Dy-Tb-Fe alloy samples were studied by using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD) and differential thermal analysis (DTA). No stable ternary compound was detected in the present experiments. The phase transformation temperatures of eight Dy-Tb-Fe alloy samples were measured. Based on the experimental results determined in this work and reported in the literature, the phase equilibria of the Dy-Tb-Fe system was calculated using the CALPHAD method. The calculated vertical sections are consistent with the experimental results determined in this work and reported in the literature. Furthermore, in combination with the experimental solidification microstructure, the solidification behavior of Dy-Tb-Fe alloy samples was analyzed through the thermodynamic calculation with the Gulliver–Scheil non-equilibrium model. The simulated results agree well with the experimental results. This indicates that the reasonable thermodynamic parameters of the Dy-Tb-Fe system were finally obtained. Full article
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23 pages, 8658 KiB  
Article
Critical Evaluation and Thermodynamic Re-Optimization of the Si–P and Si–Fe–P Systems
by Zhimin You, Hao Zhang, Senlin Cui, Zhouhua Jiang and In-Ho Jung
Materials 2023, 16(11), 4099; https://doi.org/10.3390/ma16114099 - 31 May 2023
Cited by 1 | Viewed by 983
Abstract
Thermodynamic modeling of the Si–P and Si–Fe–P systems was performed using the CALculation of PHAse Diagram (CALPHAD) method based on critical evaluation of available experimental data in the literature. The liquid and solid solutions were described using the Modified Quasichemical Model accounting for [...] Read more.
Thermodynamic modeling of the Si–P and Si–Fe–P systems was performed using the CALculation of PHAse Diagram (CALPHAD) method based on critical evaluation of available experimental data in the literature. The liquid and solid solutions were described using the Modified Quasichemical Model accounting for the short-range ordering and Compound Energy Formalism considering the crystallographic structure, respectively. In the present study, the phase boundaries for the liquidus and solid Si phases of the Si–P system were reoptimized. Furthermore, the Gibbs energies of the liquid solution, (Fe)3(P,Si)1, (Fe)2(P,Si)1, and (Fe)1(P,Si)1 solid solutions and FeSi4P4 compound were carefully determined to resolve the discrepancies in previously assessed vertical sections, isothermal sections of phase diagrams, and liquid surface projection of the Si–Fe–P system. These thermodynamic data are of great necessity for a sound description of the entire Si–Fe–P system. The optimized model parameters from the present study can be used to predict any unexplored phase diagrams and thermodynamic properties within the Si–Fe–P alloys. Full article
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16 pages, 14288 KiB  
Article
Improvement of Hot Tearing Resistance of AZ91 Alloy with the Addition of Trace Ca
by Hongchen Xiang, Wenjun Liu, Qiang Wang, Bin Jiang, Jiangfeng Song, Hang Wu, Nan Feng and Linjiang Chai
Materials 2023, 16(10), 3886; https://doi.org/10.3390/ma16103886 - 22 May 2023
Viewed by 1046
Abstract
Hot tearing is the most common and serious casting defect that restricts the light weight and integration of magnesium alloy components. In the present study, trace Ca (0–1.0 wt.%) was added to improve the resistance of AZ91 alloy to hot tearing. The hot [...] Read more.
Hot tearing is the most common and serious casting defect that restricts the light weight and integration of magnesium alloy components. In the present study, trace Ca (0–1.0 wt.%) was added to improve the resistance of AZ91 alloy to hot tearing. The hot tearing susceptivity (HTS) of alloys was experimentally measured by a constraint rod casting method. The results indicate that the HTS presents a ν-shaped tendency with the increase in Ca content, and reaches its minimum value in AZ91–0.1Ca alloy. Ca is well dissolved into α-Mg matrix and Mg17Al12 phase at an addition not exceeding 0.1 wt.%. The solid-solution behavior of Ca increases eutectic content and its corresponding liquid film thickness, improves the strength of dendrites at high temperature, and thereby promotes the hot tearing resistance of the alloy. Al2Ca phases appear and aggregate at dendrite boundaries with further increases in Ca above 0.1 wt.%. The coarsened Al2Ca phase hinders the feeding channel and causes stress concentration during the solidification shrinkage, thereby deteriorating the hot tearing resistance of the alloy. These findings were further verified by fracture morphology observations and microscopic strain analysis near the fracture surface based on kernel average misorientation (KAM). Full article
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14 pages, 4214 KiB  
Article
Investigations on Thermal Conductivity of Two-Phase WC-Co-Ni Cemented Carbides through a Novel Model and Key Experiments
by Shiyi Wen, Jing Tan, Jianzhan Long, Zhuopeng Tan, Lei Yin, Yuling Liu, Yong Du and George Kaptay
Materials 2023, 16(7), 2915; https://doi.org/10.3390/ma16072915 - 06 Apr 2023
Viewed by 1105
Abstract
Excellent thermal conductivity is beneficial for the fast heat release during service of cemented carbides. Thus, thermal conductivity is a significant property of cemented carbides, considerably affecting their service life. Still, there is a lack of systematic investigation into the thermal conductivity of [...] Read more.
Excellent thermal conductivity is beneficial for the fast heat release during service of cemented carbides. Thus, thermal conductivity is a significant property of cemented carbides, considerably affecting their service life. Still, there is a lack of systematic investigation into the thermal conductivity of two-phase WC-Co-Ni cemented carbides. To remedy this situation, we integrated experiments and models to study its thermal conductivity varying the phase composition, temperature and WC grain size. To conduct the experiments, WC-Co-Ni samples with two-phase structure were designed via the CALPHAD (Calculation of Phase Diagrams) approach and then prepared via the liquid-phase sintering process. Key thermal conductivity measurements of these prepared samples were then taken via LFA (Laser Flash Analysis). As for modeling, the thermal conductivities of (Co, Ni) binder phase and WC hard phase were firstly evaluated through our previously developed models for single-phase solid solutions. Integrating the present key measurements and models, the values of ITR (Interface Thermal Resistance) between WC hard phase and (Co, Ni) binder phase were evaluated and thus the model to calculate thermal conductivity of two-phase WC-Co-Ni was established. Meanwhile, this model was verified to be reliable through comparing the model-evaluated thermal conductivities with the experimental data. Furthermore, using this developed model, the thermal conductivity of two-phase WC-Co-Ni varying with phase-fraction, temperature and grain size of WC was predicted, which can contribute to its design for obtaining desired thermal conductivities. Full article
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