Stability of Phase Transformation Temperatures During Cycling of Ti-15.8Nb-4.94Al-0.06Sc Shape Memory Alloy

摘要

The active phase formation decreases the martensitic transformation temperatures sharply and can even suppress the martensitic transformation during thermal cycling in Ti-Nb-based alloys. No phase is observed in the present Ti-15.8Nb-4.94Al-0.06Sc alloy when it is annealed at 650 degrees C for 4h or subsequently aged at 200 and 250 degrees C for 2h. The exclusion of phase remarkably improves the stability of phase transformation temperatures during thermal cycling. The martensitic transformation start temperature of the present alloy decreases by 30 degrees C but tends to be stable gradually during the 20 thermal cycles, owing to the saturation of lattice defects.