热处理工艺对氧化物弥散强化Fe-Cr合金微观结构和致密化的影响

Effect of heat treatment on microstructure and densification of oxide dispersion strengthened Fe-Cr alloy

摘要: 将预合金粉雾化粉与Ti粉、纳米Y₂O₃粉混合后进行机械合金化，所得粉末用热等静压进行固结，采用不同的热处理参数对所得样品进行热处理。利用扫描电镜及透射电镜（TEM）等检测工具进行检测。结果表明，机械合金化中导致的孔洞会在热等静压后保留在试样基体中，随正火温度的提高，孔洞的形貌由不规则大孔洞变为细小均匀分散的小孔;在1 100 ℃下保温5 h后，孔洞粗化。TEM显示，随正火温度的提高，晶粒发生长大而粗化，并伴随着显微硬度的下降，当在1 050 ℃后继续增加温度，则硬度变化不明显。

Abstract: Fe-Cr pre-alloyed powders, pure Ti powders and nano Y₂O₃ powders were processed by mechanical alloying (MA), and then the as-milled powders were sintered by hot isostatic pressing (HIP). Different heat treatment processes were conducted on the consolidated samples. The microstructure evolution was investigated by XRD, SEM and TEM. Voids resulted from MA are remained in matrix during HIP, but the initial morphology is changed, and the regular small voids instead of irregular large voids are distributed homogeneously. Voids are linked up each other and developed into larger voids after annealing at 1 100 ℃ for 5 h. TEM images indicate that grain coarsening is occurred with the increasing normalizing temperature, while the microhardness is decreased sharply until 1 050 ℃.