【摘要】 采用氧化钇坩埚真空感应熔炼方法制备了Nb-16Si-22Ti-6Hf和Nb-16Si-22Ti-6Hf-2Cr-2Al合金铸锭,并在1500℃时进行了100 h的热处理。结果表明,铸态和热处理后的合金均由铌基固溶体(NbSS)、Nb3Si、β-Nb5Si3和γ-Nb5Si3组成。冷却速度、合金化元素及热处理均会影响合金的组织。冷却速度较低时,铸锭顶部的组织较粗大;合金化元素Cr和Al可以促进Nb3Si的共析转变,使合金铸锭的组织均匀、细化;热处理则促进Nb3Si→Nb5Si3+NbSS的发生,且Nb3Si的尺寸和体积分数均减小,边界变圆润,NbSS枝晶粗化,共晶组织由片层状变为不规则岛状。更多还原

【Abstract】 Nb-16Si-22Ti-6Hf(-2Cr-2Al) alloys were prepared using vacuum induction melting in Y2O3 crucible,and the heat treatment was conducted at 1500℃ for 100h.The constituent phases analysis show that the ingots are composed of the phases of Nb solid solution(NbSS)、 Nb3Si、 β-Nb5Si3 and γ-Nb5Si3.The cooling rate,alloying elements and heat treatment have effects on the microstructures of the ingots.The lower the cooling rate is,the coarser the microstructures at the top of the ingots are.The addition of Cr and Al promotes the eutectoid reaction,resulting in the much more homogenous and finer of the microstructures.While the heat treatment promotes the eutectoid reaction of Nb3Si→Nb5Si3+NbSS,leading to the decrease in the dimension and the volume fraction of Nb3Si,and the smooth of the boundary.Furthermore,the NbSS dendrites coarsen slightly,and the lamellar-like eutectic structures change into irregular island-like during the heat treatment.更多还原