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

Through the research of hot deformation behavior of Nb-16Si-22Ti-2Cr-2Al-2Hf-xFe (x=0, 1, 2, 3, 5) alloys, the hot working diagrams of these alloys were made, which would provide a theoretical basis for subsequent design and hot working study of Nb-Si alloys. The maximum dissipative efficiency factor eta 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 contents, 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.