通过对Cr3C2/Ni3Al复合材料在1000℃进行长期时效和氧化实验, 分别考察了该材料的高温相稳定性和化学稳定性. 结果表明, 经1000℃长期时效后, Cr3C2/Ni3Al复合材料中的Cr3C2强化相保持稳定,而基体中则析出一定量的γ相, 该相的析出强化了Ni3Al基体, 从而使得复合材料的硬度得到进一步提高. Cr3C2/Ni3Al复合材料具有优良的高温抗氧化性能, 其表面形成以α-Al2O3为主的致密氧化膜, 在空气中的氧化速率仅为Ni3Al合金的1/2. 分析认为, Cr3C2在堆焊过程中发生溶解, 导致部分Cr固溶于Ni3Al合金基体中,促进了α-Al2O3的形成, 从而改善了复合材料的抗氧化性. Cr3C2具有良好的高温化学稳定性并与Ni3Al基体有较好的氧化协同性, 从而可得到基体有力支撑以发挥抵抗磨损的作用. 优良的高温稳定性使得Cr3C2/Ni3复合材料适于在1000℃的高温环境下长期服役.
The phase stability and chemical stability of Cr3C2/Ni3Al composite at 1000℃ have been investigated through long-term aging and oxidation experiment. After long-term aging at 1000℃，chromium carbides kept stable, a few gamma phases separated out and strengthened the Ni3Al matrix, which resulted in the harness of Cr3C2/Ni3Al composite increase. On the other hand, Cr3C2/Ni3Al composite possessed good oxidation resistance. The protective oxides that mainly consisted of α-Al2O3 were formed and the chromium carbides exhibited good anti-oxidation stability and oxidation synergism with Ni3Al matrix. The analyse shows that the chromium carbides are dissolved during welding and some dissolved Cr enter into Ni3Al matrix. The existence of Cr promotesα-Al2O3 formation, which improves the oxidation resistance of the composite obviously. The oxidation rate of the Ni3Al alloy is two times greater than that of the composite in air. Good phase stability and chemical stability make Cr3C2/Ni3Al composite be suitable for long-term service at 1000℃.
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