High Temperature Deformation Behavior and Microstructural Evolution of Nb-۱۰Hf-۱Ti Alloy Produced by Vacuum Arc Melting

The present work deals with the hot deformation behavior of commercial Nb alloy C-۱۰۳ and its microstructure evolution during uniaxial compression tests in the temperature range of ۷۰۰-۱۱۰۰ °C and the strain rate range of ۰.۰۰۱-۰.۴ s-۱. Strain rate sensitivity, calculated from the compression tests data, was almost constant and showed a negative value in the temperature range of ۷۰۰-۹۰۰ °C but increased significantly beyond ۹۰۰ °C. Dynamic strain aging was found to have a predominant effect up to ۹۰۰ °C, beyond which dynamic recovery and oxidation influenced the compressive properties. The microstructure of the deformed samples showed indications of dynamic recrystallization within the high strain rate sensitivity domain and features of flow instability in the regime of low strain rate sensitivity. The ۹۵۰–۱۰۰۰ °C temperature range and strain rate range of ۰.۰۰۱-۰.۱ s-۱ were suggested as suitable hot deformation conditions. The constitutive equation was established to describe the alloy's flow behavior, and the average activation energy for plastic flow was calculated to be ۲۶۷ kJ/mol.

Keywords:

Niobium alloy , Hot deformation , Strain rate sensitivity , Dynamic recrystallization , Constitutive equation