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Article

Effect of Graphite Powder Addition on Microstructure and Room Temperature Mechanical Properties of Ti-45Al-8Nb Alloys

by
Sheng Wang
1,
Yuliang Jin
2,*,
Xiguo Chen
1 and
Xiaohong Yang
3,4,*
1
Department of Mechanical Engineering, Quzhou College of Technology, Quzhou 324000, China
2
School of Materials Science and Engineering, Anhui Polytechnic University, Wuhu 241000, China
3
Academician Expert Workstation, Jinhua Polytechnic, Jinhua 321017, China
4
Key Laboratory of Crop Harvesting Equipment Technology of Zhejiang Province, Jinhua 321017, China
*
Authors to whom correspondence should be addressed.
Coatings 2024, 14(1), 21; https://doi.org/10.3390/coatings14010021
Submission received: 1 December 2023 / Revised: 20 December 2023 / Accepted: 21 December 2023 / Published: 25 December 2023
(This article belongs to the Section Ceramic Coatings and Engineering Technology)
Browse Figures
Versions Notes

Abstract

:
The enhancement of the mechanical properties of TiAl alloys through the introduction of a second-phase reinforcement is highly essential. In this paper, using graphite powder as a carbon source, the Ti2AlC phase is introduced to improve the compression and friction properties of the TiAl alloy. Concurrently, the effects of graphite powder additions on the microstructure and room-temperature mechanical properties of Ti-45Al-8Nb-xC (mass%) alloys are investigated. The results show that as the volume fraction of Ti2AlC and the interdendritic γ phase increases, the length–diameter ratio of the Ti2AlC phase decreases with increases in the graphite powder addition. The addition of graphite powder results in a refining effect on the grain size and lamellar spacing of the Ti-45Al-8Nb-xC (mass%) alloys. As the graphite powder content increases from 0 to 0.9 mass%, the microhardness increases from 557 HV to 647 HV. The room-temperature compressive strength and strain of the Ti-45Al-8Nb-xC (mass%) alloys first increase and then decrease with the addition of graphite powder. Specifically, when the content of graphite powder is 0.6 mass%, the alloy exhibits a maximum compressive strength and strain of 1652 MPa and 22.2%, respectively. Compared with the alloy without the graphite powder addition, the compressive strength and strain are improved by 37.7% and 62.1%, respectively. The wear resistance of the alloys is improved through the addition of graphite powder and the wear rate decreases from 5.062 to 2.125 × 10−4 mm3·N−1·m−1 as the content of graphite powder increases from 0 to 0.9 mass%.

1. Introduction

High-Nb TiAl alloys are expected to replace Ni-based superalloys to become high-temperature structural materials with great potential in the automotive and aerospace industries due to their low density, high specific strength, and good creep resistance [1,2,3,4]. However, its strength, plasticity, and wear properties are still not balanced at room temperature, which limits the wide application of high-Nb TiAl alloys in industry [5,6,7]. Therefore, a means to effectively enhance the comprehensive properties of high-Nb-TiAl alloys and promote their engineering applications is urgently needed.
TiAl matrix composites are a new type of material in which fibers (such as SiC) or ceramic particle reinforcements are introduced into the TiAl matrix to enhance the properties of the alloy. They have received much attention from researchers because they combine the advantages of intermetallic and reinforcing phases [8,9]. Compared with fiber reinforcement, particle reinforcement has better thermal expansion coefficient fitness and less reactivity with the matrix and the preparation process is simpler and less costly [10,11,12]. Hence, the addition of particle reinforcement to the TiAl matrix becomes an important means to improve the properties of TiAl alloys. Among the many reinforcing phases, binary ceramic phases are often used to improve the strength and wear resistance of TiAl alloys at room and elevated temperatures due to their higher hardness, specific stiffness, specific strength, and excellent wear resistance [13,14,15,16,17].
In recent years, binary MAX phases (such as Ti2AlC and Ti2AlN) have been found to have a high modulus of elasticity and possess both metallic and ceramic properties [18,19,20]. In addition, Ti2AlC has a similar coefficient of thermal expansion as TiAl alloys and better chemical compatibility, which is beneficial to avoid stress concentration at the interface between the reinforcing phase and matrix and is an ideal reinforcing phase for the preparation of TiAl-based composites [21]. Fang et al. [22] prepared Ti2AlC/TiAl composites through vacuum arc melting and found that the composites reached a maximum compressive strength of 2324.3 MPa when the C content was 1.5 mass% and a maximum compression strain of 28.1% when the C content was 2.5 mass%. Gao et al. [23] prepared Ti2AlC/TiAl composites through powder metallurgy; the results showed that the composites exhibited a good strength–plasticity balance and the room-temperature compressive strength and strain of the composites were improved by 10.1% and 5.5%, respectively. Wear behavior is an inevitable problem for high-temperature structural components, e.g., fatigue cracks on the surface of engine turbine blades due to abrasive wear will lead to engine failures [24]. Therefore, it is crucial to improve the wear properties of TiAl alloys by introducing ceramic particles. Cheng et al. [25] prepared Ti2AlC/TiAl composites with 20 vol% and 40 vol% volume fractions in reinforcing phases using hot press sintering; the results showed that 40 vol% Ti2AlC/TiAl composites showed a significant increase in wear resistance and that the abrasion mechanism was oxidation and adhesive wear.
In summary, the introduction of ceramic particles as reinforcement can effectively enhance the compressive and tribological properties of TiAl alloys. Therefore, in this paper, an in situ Ti2AlC-reinforced high-Nb TiAl alloy was prepared using vacuum arc melting with graphite powder as the C source. The effect of graphite powder content on the microstructure, compression, and tribological behavior at room temperature was investigated and the strengthening mechanism was discussed. These works aim to add graphite powder to form Ti2AlC ceramic particles to enhance the mechanical properties of TiAl alloys and to provide a theoretical basis for the further understanding of the strengthening and tribological behavior of TiAl alloys.

2. Materials and Methods

The alloy ingots with nominal compositions of Ti-45Al-8Nb-xC (x = 0, 0.3, 0.6, and 0.9, mass%) were prepared through vacuum arc melting using high-purity Ti, Al, and Nb particles (≥99.98% purity) and graphite powder (≥99.9% purity) as raw materials. The melting of each alloy ingot was repeated four times to ensure the homogeneity of the components.
Samples for microstructural studies and property tests were taken from almost the same geometrical position in the ingot using electro-discharge wire cutting. Ingots for microstructural characterization were ground, polished, and then etched using Kroll’s reagent (5% HF + 10% HNO3 + 85% H2O, vol.%). The microstructure and elemental composition of the alloys were investigated using scanning electron microscopy (SEM, Hitachi SU8000, Tokyo, Japan) equipped with an energy dispersive spectrometer (EDS). The phase composition of the alloy was determined using an X-ray diffractometer (XRD, Bruker D8, Karlsruhe, Germany) with a scanning angle of 20–90°.
The hardness of the alloys was measured using a DUH-211S micro-dynamic hardness tester with a pressure setting of 100 mN, an indentation rate of 5 mN/s, and a dwell time of 10 s; at least 10 tests were performed for each sample. The compression tests were carried out on an MTS-370.10 (Eden Prairie, MN, USA) universal test machine at room temperature with dimensions of Φ 4 mm × 6 mm and a constant strain rate of 0.2 mm/min. The lamellar spacing, phase volume fraction, and length–diameter ratio of Ti2AlC were determined using ImageJ 180 software. Friction tests were conducted using a tribometer (HT-1000, Keyence, Shanghai, China) at room temperature regarding the air. The counterpart material was a Si3N4 ball with a diameter of 4 mm. The radius of the wear track was 3 mm, the applied load was 6.5 N, and it was slid at 600 r/min for 30 min. The wear track profiles of the samples were measured using a Keyence 3D topographical scanner (VHX-2000, Osaka, Japan) and the cross-sectional area of the wear track was calculated. The wear rate W was calculated according to the equation W = V/P·2πrt where V denotes the wear volume (mm3), P is the applied load (N), r is the radius of the wear track, R is the rotational speed, and t is the wear time.

3. Results

3.1. Microstructures

Figure 1 shows the XRD patterns of Ti-45Al-8Nb-xC alloys with different graphite powder additions. The Ti-45Al-8Nb alloy mainly consisted of the α2-Ti3Al phase and γ-TiAl phase. The intensity of the γ-phase diffraction peaks is enhanced with the addition of graphite powder. The diffraction peaks of the Ti2AlC phase appeared at 2θ = 33°, 39°, and 61° when the graphite addition was 0.6 mass% [26]. The highest Ti2AlC phase diffraction peak intensity was observed when the graphite powder addition increased to 0.9 mass%. This indicates that the increase in C content leads to an increase in the volume fraction of the γ phase and Ti2AlC phase. The B2 phase diffraction peaks were not observed in the XRD results due to the limited amount of B2 phase in the alloys that could not be detected using an X-ray. It has been shown that Nb has high solid solubility in TiAl [27]. In the Ti-45Al-8Nb alloy, Nb is mainly solid-solved in the α2 and γ phases, with a small amount of segregation in the B2 phase.
Figure 2 illustrates the SEM images of the Ti-45Al-8Nb alloy after etching with different graphite powder contents. The microstructure of the alloys is refined and the bar-like precipitation phase and intergranular γ phase gradually increase with the addition of graphite powder. When the content of graphite powder increases from 0.3 to 0.9 mass%, the precipitation phase coarsening and aggregation are observed in Figure 2b–d. In addition, the morphology of the precipitated phase changes with increasing graphite powder content. The morphology of the precipitated phase is mainly in the form of long bars when the addition of graphite powder is 0.3 mass%. As the graphite powder content is further increased to 0.9 mass%, the morphology of the precipitated phase was shortened in length and increased in diameter.
Figure 3 shows the SEM micrographs of Ti-45Al-8Nb alloy with 0.6 mass% graphite powder addition through EDS points and line inspections. Table 1 shows the EDS results for points A and B in Figure 3a. The EDS point analysis reveals that the precipitated phase (B) contains approximately 21.2% C, 46.6% Ti, 26.6% Al, and 5.6% Nb, which is the value of the Ti2AlC phase. Similarly, the atomic ratio of Ti, Al and C in white particle A is close to 1:0:1. Combined with the results of the line scan in Figure 3b, it is found that the content of elemental C in the vicinity of the white particles is elevated, while the content of elemental Al decreases; therefore, it is inferred that the white particles are part of the TiC phase. It has been shown [28] that in the cast Ti-Al-C system, the formation process of the Ti2AlC phase is as follows: When the temperature is higher than 600 °C, Al melts and reacts with Ti to generate liquid TiAl3. As the temperature reaches 900 °C, Ti reacts with C to form TiC. When the temperature rises to 1200 °C, TiC, Ti, and liquid TiAl3 react to precipitate the Ti2AlC phase. With a further increase in temperature, the Ti2AlC phase decomposes into TiC and liquid TiAl at 1625 °C. Meanwhile, TiC is a solid form distributed in the molten metal due to its high melting point (approximately 3200 °C). During solidification, TiC reacts again with liquid TiAl to form the Ti2AlC phase. Therefore, it can be indicated that the white particles are the products of the incomplete reactions between TiC and liquid TiAl.
To further investigate the effects of graphite powder on the microstructure of Ti-45Al-8Nb alloys with different additions, the lamellar colony size (LC), γ/α2 lamellar spacing (LS), volume fraction, and length–diameter ratio of the Ti2AlC phase of the alloys were measured and statistically analyzed and the mechanism of microstructure evolution was determined. Figure 4 and Table 2 show the statistical results of the alloy lamellar colony size and lamellar spacing. The lamellar colony size of the Ti-45Al-8Nb alloy matrix decreases from 257.6 to 38.1 μm as the addition of graphite powder increases from 0 to 0.9 mass%. According to the pseudo-binary phase diagram of the Ti-xAl-8Nb (mass%) alloy, the solidus temperature of the Ti-45Al-8Nb alloy is lower than the temperature for forming the Ti2AlC phase. Based on the above analysis, the solidification path of the Ti2AlC-enforced Ti-45Al-8Nb alloy is deduced as follows: L + TiC→L + β + Ti2AlC→β + α + Ti2AlC→ β + α + γ + Ti2AlC→β + α2 + γ + Ti2AlC→B2 + (α2 + γ) +γ + Ti2AlC. The Ti2AlC phase was initially generated as the nucleation site in the microstructure of the Ti-45Al-8Nb alloy; with the addition of graphite powder, the volume fraction of the Ti2AlC phase increased and the increase in nucleation sites was conducive to grain refinement. In addition, during the solid-state phase transformation process, the Ti2AlC phase hinders the movement of grain boundaries and inhibits grain growth, thereby refining the microstructure.
Furthermore, when the addition of graphite powder is less than 0.6 mass%, the lamellar spacing decreases when the increasing graphite powder content, with the lowest level at 152.1 nm. However, when the addition of graphite powder is increased to 0.9 mass%, the lamellar spacing increases to 269.3 nm. It has been reported [29] that the lamellar structure of TiAl alloy is formed through the precipitation of the γ phase from the α phase and grows through the mechanism of a step-bump twist. When C is added to the alloy matrix, the interstitial C atoms tend to agglomerate at the interface of the lamellae, contaminating the attachment position of Ti or Al atoms, reducing the lateral growth rate of the γ lamellae [30], and thus reducing the γ/α2 lamellar spacing. In addition, it can be seen from the previous analyses that local agglomeration of Ti2AlC in the alloy matrix occurs, resulting in excessive carbon content in the local region. However, the formation of the Ti2AlC phase consumes a large amount of Ti, which makes the alloy matrix rich in Al and poor in Ti. The increase in Al content will increase the lamellar spacing of the TiAl alloy and eventually lead to a coarse lamellar structure.
Figure 5 and Table 3 show the statistical results of the volume fraction and length–diameter ratio of the Ti2AlC phase for Ti-45Al-8Nb alloys with different graphite powder contents. The phase volume fraction of Ti2AlC increases from 1.6% to 12.2% and the length–diameter ratio decreases from 35 to 4.8 when increasing the addition of graphite powder from 0.3 mass% to 0.9 mass%. This is because of the increase in TiC content in the molten alloy with the addition of graphite powder; TiC acts as a nucleation site for Ti2AlC during solidification, resulting in a decrease in the Ti2AlC length–diameter ratio.

3.2. Mechanical Properties

The microhardness values of the Ti-45Al-8Nb alloy with different graphite powder contents are shown in Figure 6. The microhardness of the alloy is enhanced through the addition of graphite powder. The microhardness of the alloy increased from 557 HV to 647 HV when the addition amount was increased from 0 mass% to 0.9 mass%, which is an increase of approximately 16%. The improvement in the microhardness of the alloy is mainly attributed to the following two points. On the one hand, the addition of graphite powder refines the grains, resulting in an increase in the number of grain boundaries in the alloy and hindering the movement of dislocations, thus improving the microhardness of the alloy [31]. On the other hand, the addition of graphite powder increases the volume fraction of the Ti2AlC phase in the alloy matrix. The Ti2AlC phase is a high-hardness ceramic particle, which improves the microhardness of the alloy.
The compression test results of Ti-45Al-8Nb alloys with different graphite powder contents at room temperature are shown in Figure 7 and Table 4. As shown in Figure 7, the nominal yield strength, compressive strength, and strain of the alloy increase with the addition of graphite powder. When the graphite powder addition increased to 0.6 mass%, the compressive strength and strain of the alloy reached the maximum values of 1652 MPa and 22.2%, respectively. Compared with the Ti-45Al-8Nb alloy without graphite powder, the compressive strength is increased by approximately 37.7% and the compression strain is increased by approximately 62.1%. However, when the graphite powder content was further increased to 0.9 mass%, the compressive strength and strain decreased to 1524 MPa and 21.5%, respectively.
Figure 8 shows the fracture morphologies of the Ti-45Al-8Nb-xC alloy after compression testing at room temperature. The morphology of the fracture contains a trans-lamellar fracture and an interlamellar fracture, which is a brittle fracture. The alloy shows many smooth cleavage surfaces when the graphite powder content is 0 mass%. With the addition of graphite powder, the cleavage surface of the alloy decreases and there are steps. This indicates that the cracks are deflected several times inside the alloy. Figure 8e,f show the magnification of the fracture morphology of the alloys with graphite powder contents of 0.6 and 0.9 mass%. The fracture and shedding of the Ti2AlC phase can be observed. This shows that the strengthening and toughening mechanism of the Ti2AlC phase during deformation is to generate pull-out, interlayer tearing, and debonding.
Figure 9 shows the friction coefficient time curves of Ti-45Al-8Nb alloys with different graphite powder additions. When the content of graphite powder increased from 0 to 0.6 mass%, the friction coefficient of the alloy gradually decreased. Then, when the content of graphite powder increased to 0.9 mass%, the friction coefficient of the alloy increased slightly. This shows that the addition of C has little effect on the friction coefficient when it exceeds 0.6 mass%.
The profile of the wear surface of the Ti-45Al-8Nb alloy with different graphite powder contents measured using a 3D surface profilometer is shown in Figure 10. The measured profile area was used to calculate the wear rate. The results of the friction coefficient and wear rate are listed in Table 5. The wear rate decreased from 5.062 to 2.125 × (10−4 mm3·N−1·m−1) when the addition of graphite powder increased from 0 to 0.9 mass%. Compared with the alloy without graphite powder, the wear rate of the alloy with 0.9 mass% graphite powder decreased by 42%, which indicates that the addition of graphite powder is conducive to the enhancement of the wear resistance of Ti-45Al-8Nb alloy.
SEM images of the wear-track surfaces of Ti-45Al-8Nb alloys with different graphite powder additions are shown in Figure 11. Wear debris and grooves are observed on the wear surfaces of all alloys. This shows that the main wear mechanism of the alloy at room temperature is plowing wear. The reason for the formation of grooves is that the hardness of the Si3N4 balls (15 GPa) [32] is higher than that of the TiAl specimen (5.9 GPa) and the Si3N4 balls can press into the sample and plow the surface under the normal load. The composition of the debris on the wear surface is identified through EDS. The results show that the compositions of the bulk debris are mainly TiAl and Si3N4 (in Figure 11b). As shown in Figure 11a,c,e,g, the worn debris on the wear surface of the sample gradually decreases with increasing graphite powder content. However, the abrasive particles remaining in the wear track will further wear the sample surface, leading to an increase in the coefficient of friction [33]; therefore, the alloy with graphite powder added exhibits a lower coefficient of friction. The convex Ti2AlC phase was observed on the wear surface of the samples with high content graphite powder (0.6 and 0.9 mass%) and some grooves were separated at the Ti2AlC phase. Since the hardness of Ti2AlC (11.4 GPa) [34] phase is higher than that of the Ti-45Al-8Nb alloy matrix, a large number of convex Ti2AlC phases on the surface of the alloy can hinder the direct contact between the Si3N4 balls and the alloy, thus reducing the plowing of the alloy by the Si3N4 balls. Therefore, the worn debris on the surface of the wear track gradually decreases with the addition of graphite powder and the wear rate shows a gradually decreasing trend.

4. Conclusions

Ti-45Al-8Nb-xC (x = 0, 0.3, 0.6, and 0.9, mass%) was prepared through vacuum arc melting and the effects of graphite powder additions on the microstructure and room-temperature mechanical properties of Ti-45Al-8Nb-xC (mass%) alloys were investigated. The main conclusions are summarized as follows:
(1)
The addition of graphite powder leads to an increase in the volume fraction of the Ti2AlC phase and intergranular γ-phase in the Ti-45Al-8Nb-xC alloy and a decrease in the length–diameter ratio of the Ti2AlC phase. The addition of graphite powder can refine the grains, reduce the lamellar spacing, and improve the hardness of the alloy.
(2)
The compressive strength and strain of the Ti-45Al-8Nb-xC alloys exhibit an increasing and then decreasing trend with the addition of graphite powder. When the content of graphite powder is 0.6 mass%, the alloy exhibits a maximum compressive strength and strain of 1652 MPa and 22.2%, respectively. Compared with the Ti-45Al-8Nb alloy without graphite powder, the improvement is approximately 37.7% and 62.1%, respectively.
(3)
The tribological properties of TiAl alloys can be significantly enhanced by the in situ formation of Ti2AlC with the addition of graphite powder. The reduction in the coefficient of friction and wear rate is 18% and 46%, respectively, when graphite powder is added at 0.9 mass%.
Based on these conclusions, the addition of graphite powder enhanced the compression and friction properties of TiAl alloys. Simultaneously, it provides a theoretical basis for further understanding the compression and tribological behavior of second-phase reinforced TiAl alloys.

Author Contributions

Conceptualization, S.W.; methodology, Y.J.; validation, X.C.; investigation, resources, X.Y. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Public Welfare Technology Research Project of Zhejiang Province (Funder: Sheng Wang. No. LGC21E050002) and the Science and Technology plan project of Quzhou (Funder: Sheng Wang. Nos. 2023NC07, 2022NC06).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The authors confirm that the data supporting the findings of this study are available within the article.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. XRD patterns of Ti-45Al-8Nb alloys with different graphite powder contents.
Figure 1. XRD patterns of Ti-45Al-8Nb alloys with different graphite powder contents.
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Figure 2. Microstructure of Ti-45Al-8Nb-xC alloy with different graphite powder contents. (a) 0 mass%; (b) 0.3 mass%; (c) 0.6 mass%; and (d) 0.9 mass%.
Figure 2. Microstructure of Ti-45Al-8Nb-xC alloy with different graphite powder contents. (a) 0 mass%; (b) 0.3 mass%; (c) 0.6 mass%; and (d) 0.9 mass%.
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Figure 3. Compositional analysis of the precipitated phase of Ti-45Al-8Nb alloy with 0.6 mass% graphite powder addition of (a) the EDS point, A is TiC, B is Ti2AlC. (b) the line inspection.
Figure 3. Compositional analysis of the precipitated phase of Ti-45Al-8Nb alloy with 0.6 mass% graphite powder addition of (a) the EDS point, A is TiC, B is Ti2AlC. (b) the line inspection.
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Figure 4. Statistical analysis of the average lamellar colony size and lamellar spacing for Ti-45Al-8Nb alloys with different graphite powder contents.
Figure 4. Statistical analysis of the average lamellar colony size and lamellar spacing for Ti-45Al-8Nb alloys with different graphite powder contents.
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Figure 5. Statistical analysis of the Ti2AlC phase volume fraction and length–diameter ratio for Ti-45Al-8Nb alloys with different graphite powder contents.
Figure 5. Statistical analysis of the Ti2AlC phase volume fraction and length–diameter ratio for Ti-45Al-8Nb alloys with different graphite powder contents.
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Figure 6. Microhardness of the Ti-45Al-8Nb alloy with different graphite powder contents.
Figure 6. Microhardness of the Ti-45Al-8Nb alloy with different graphite powder contents.
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Figure 7. Room temperature compressive stress–strain curves of Ti-45Al-8Nb alloys with different graphite powder contents.
Figure 7. Room temperature compressive stress–strain curves of Ti-45Al-8Nb alloys with different graphite powder contents.
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Figure 8. Room temperature compression fracture morphologies of Ti-45Al-8Nb-xC alloys. (a) A total of 0 mass%; (b) 0.3 mass%; (c,e) 0.6 mass%; and (d,f) 0.9 mass%.
Figure 8. Room temperature compression fracture morphologies of Ti-45Al-8Nb-xC alloys. (a) A total of 0 mass%; (b) 0.3 mass%; (c,e) 0.6 mass%; and (d,f) 0.9 mass%.
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Figure 9. Friction coefficient time curve of Ti-45Al-8Nb alloys with different graphite powder contents.
Figure 9. Friction coefficient time curve of Ti-45Al-8Nb alloys with different graphite powder contents.
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Figure 10. Wear profile of Ti-45Al-8Nb alloy with different graphite powder contents. (a) A total of 0 mass%; (b) 0.3 mass%; (c) 0.6 mass%; and (d) 0.9 mass%.
Figure 10. Wear profile of Ti-45Al-8Nb alloy with different graphite powder contents. (a) A total of 0 mass%; (b) 0.3 mass%; (c) 0.6 mass%; and (d) 0.9 mass%.
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Figure 11. Surface morphology of wear tracks of Ti-45Al-8Nb alloy with different graphite powder additions. (a,b) A total of 0 mass%; (c,d) 0.3 mass%; (e,f) 0.6 mass%; and (g,h) 0.9 mass%.
Figure 11. Surface morphology of wear tracks of Ti-45Al-8Nb alloy with different graphite powder additions. (a,b) A total of 0 mass%; (c,d) 0.3 mass%; (e,f) 0.6 mass%; and (g,h) 0.9 mass%.
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Table 1. EDS point scans of the points in Figure 3a (mass%).
Table 1. EDS point scans of the points in Figure 3a (mass%).
PositionCAlNbTi
A37.754.074.8753.31
B21.226.65.5446.66
Table 2. Statistical results of the average lamellar colony size and lamellar spacing at different graphite powder contents.
Table 2. Statistical results of the average lamellar colony size and lamellar spacing at different graphite powder contents.
Content/Mass%LC/μmLS/μm
0257.6332.8
0.366.9272.6
0.644.4152.1
0.938.1269.3
Table 3. The phase volume fraction of Ti2AlC and length–diameter ratio results for Ti-45Al-8Nb alloys with different graphite powder contents.
Table 3. The phase volume fraction of Ti2AlC and length–diameter ratio results for Ti-45Al-8Nb alloys with different graphite powder contents.
Content/Mass%Phase Volume Fraction/vol.%Length–Diameter Ratio/vol.%
0.31.635
0.65.312.6
0.912.24.8
Table 4. Room temperature compressive mechanical properties of Ti-45Al-8Nb alloys with different graphite powder contents.
Table 4. Room temperature compressive mechanical properties of Ti-45Al-8Nb alloys with different graphite powder contents.
Content/Mass%Nominal Yield Strength/MPaCompressive Strength/MPaCompressive Strian/%
01036120013.7
0.31088133214.6
0.61205165222.2
0.9955152421.5
Table 5. Friction properties of the Ti-45Al-8Nb alloys with different graphite powder contents.
Table 5. Friction properties of the Ti-45Al-8Nb alloys with different graphite powder contents.
Content/Mass%Friction CoefficientWear Rates/10−4 mm3·N−1·m−1
00.2895.062
0.30.2502.77
0.60.2312.40
0.90.2372.125
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Wang, S.; Jin, Y.; Chen, X.; Yang, X. Effect of Graphite Powder Addition on Microstructure and Room Temperature Mechanical Properties of Ti-45Al-8Nb Alloys. Coatings 2024, 14, 21. https://doi.org/10.3390/coatings14010021

AMA Style

Wang S, Jin Y, Chen X, Yang X. Effect of Graphite Powder Addition on Microstructure and Room Temperature Mechanical Properties of Ti-45Al-8Nb Alloys. Coatings. 2024; 14(1):21. https://doi.org/10.3390/coatings14010021

Chicago/Turabian Style

Wang, Sheng, Yuliang Jin, Xiguo Chen, and Xiaohong Yang. 2024. "Effect of Graphite Powder Addition on Microstructure and Room Temperature Mechanical Properties of Ti-45Al-8Nb Alloys" Coatings 14, no. 1: 21. https://doi.org/10.3390/coatings14010021

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