Nb-16Si-22Ti-2Cr-2Al-2Hf-xFe合金热加工性能研究

A Study on Hot Workability of Nb-16Si-22Ti-2Cr-2Al-2Hf-xFe Alloys

摘要:

通对五种不同铁含量铌硅合金的热变形行为的探索和研究，本文分别绘制了五种铌硅合金的热加工图，为后续铌硅合金的设计及热加工研究提供了理论依据。合金耗散效率因子η的最大值出现在低应变速率及高温区域；最小值则出现在低温和高应变速率区域。不同Fe含量合金的热加工图中均存在失稳变形区，主要分布于应变速率高和变形温度低的区域，与低耗散效率因子区域重合。失稳区晶粒明显拉长，晶界出现弯曲扭折现象，晶粒大小分布不均匀，发生了局部塑性流动。稳定变形区存在链状的动态再结晶组织，细小的再结晶晶粒沿晶界分布，随着变形温度的升高和应变速率的降低，动态再结晶晶粒的尺寸增大。

Abstract:

Through the research of hot deformation behavior of Nb-16Si-22Ti-2Cr-2Al-2Hf-xFe(x=0、1、2、3、5) alloys, this paper made the hot working diagrams of these alloys which would provides a theoretical basis for subsequent Nb-Si alloys′design and hot working study. The maximum dissipative efficiency factor η appears in the region of low strain rate and high temperature; the minimum appears in low temperature and high strain rate region. There are unstable regions in the thermal processing map of the alloys with different Fe content, mainly distributed in the regions with high strain rate and low temperature, coinciding with the low dissipative efficiency factor regions. The grains in the unstable regions are obviously elongated and the grain boundaries are curved. The grain size is uneven and local plastic flow occurs. The dynamic recrystallization structure exists in the stable deformation zone as well as the fine recrystallized grain is distributed along the grain boundary. With the increase of the deformation temperature and the decrease of the strain rate, the size of the dynamic recrystallization grain increases.