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采用机械合金化+热压工艺制备出成分为Cr-12Nb的Cr/NbCr2合金。对该合金进行800℃保温不同时间的真空热暴露实验,研究了热暴露对合金组织与性能的影响。结果表明,合金在前30h的热暴露过程中析出了细小的Laves相NbCr2,随热暴露时间的延长,Laves相NbCr2不再析出,并发生聚集长大。Cr-12Nb合金的致密度在热暴露过程中稍有增加,而维氏硬度随热暴露时间的延长先升高后下降,但整体均高于热暴露前,维氏硬度在热暴露50h后达到6.1GPa,较未热暴露提高了3.3%。Cr-12Nb合金的室温压缩屈服强度、抗压强度和塑性应变随热暴露时间的延长先上升后下降,屈服强度和抗压强度整体而言均高于未热暴露时的强度。热暴露50 h后合金的屈服强度和抗压强度分别从热暴露前的1843MPa和1911MPa提高至1884MPa和2372MPa。塑性应变在热暴露10h后达到最大值13.2%,热暴露50h后下降至8.1%,较热暴露前下降了33.6%。
The Cr / NbCr2 alloy with the composition of Cr-12Nb was prepared by mechanical alloying and hot pressing. The alloy was subjected to vacuum heat exposure at 800 ℃ for different time, and the effects of heat exposure on the microstructure and properties of the alloy were studied. The results show that during the first 30h heat treatment, the alloy precipitates fine Nb2O5 phase Laves phase NbCr2. With the increase of heat exposure time, NbCr2 phase of Laves phase is no longer precipitated and aggregates and grows. The density of Cr-12Nb alloy slightly increased during the heat exposure, while the Vickers hardness increased first and then decreased with the increase of heat exposure time, but the overall hardness of Cr-12Nb alloy was higher than that before heat exposure, and Vickers hardness reached after 50h heat exposure 6.1GPa, 3.3% higher than the unexposed exposure. The compressive yield strength, compressive strength and plastic strain of Cr-12Nb alloy first increase and then decrease with the extension of heat exposure time, and the yield strength and compressive strength of the Cr-12Nb alloy as a whole are higher than that of the non-heat-exposed alloy. After 50 h thermal exposure, the yield strength and compressive strength of the alloy increased from 1843 MPa and 1911 MPa before heat exposure to 1884 MPa and 2372 MPa, respectively. The plastic strain reached the maximum value of 13.2% after heat exposure for 10 hours, decreased to 8.1% after heat exposure for 50 hours and decreased by 33.6% compared with that before heat exposure.