摘要
研究了通过机械合金化+热压工艺制备的细晶Cr-NbCr_2合金的热稳定性。结果表明:热暴露过程中,Cr基体的颗粒尺寸有一定程度的长大,而Laves相NbCr_2颗粒由于其高热稳定性无明显变化。随着热暴露的进行,Cr基体颗粒与Laves相NbCr_2颗粒间压应力增加,使得基体和Laves相中分别出现了位错和层错/孪晶结构。颗粒尺寸的变化和晶体缺陷的出现,使得Cr-NbCr_2合金在800~1200℃热暴露50 h后仍具有较高的抗压强度,屈服强度和良好的塑性。但随着热暴露的继续延长,此时颗粒的长大成为主导因素,Cr-NbCr_2合金的屈服强度和塑性明显下降。
Thermal stability of the fine-crystal Cr-NbCr_2 alloy prepared by mechanical alloying and hot pressing was researched. The results show that the grain size of Cr matrix has a certain degree of growing up after the thermal exposure, while the particle size of Laves phase NbCr_2 has no obvious change due to its high thermal stability. At the same time, the dislocation in the Cr matrix and the stacking faults/twins in the Laves phase NbCr_2 particles appear in the as-thermally exposed microstructure because of the increase of the compressive stress between Cr matrix and NbCr_2 particles. Due to the variation in particle size and the occurrence of crystal defects, the Cr-NbCr_2 alloy can keep higher compressive strength, yield strength and plastic strain after thermal exposure from 800 °C to 1200 °C for 50 h. However, the yield strength and plastic strain of the Cr-NbCr_2 alloy decline obviously by prolonging the thermal exposure because the growth of grains becomes the determining factor of properties.
引文
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