Martensitic transformation of a Ti-rich Ti 40.5 Ni 49.5 Zr 10 shape memory alloy
Journal
Journal of Alloys and Compounds
Journal Volume
297
Journal Issue
1-2
Pages
294-302
Date Issued
2000
Author(s)
Hsieh S.F.
Abstract
Ti40.5Ni49.5Zr10 alloy undergoes a B2↔B19′ one-stage martensitic transformation with Ms≈100 °C. This alloy exhibits about 90% shape memory recovery even though many (Ti,Zr)2Ni particles exist around (Ti,Zr)Ni grain boundaries. The B19′ martensite structure is calculated with a = 0.295 nm, b = 0.408 nm, c = 0.491 nm and β = 97.4°. Martensitic transformation temperatures decrease with increasing aging time at 300 °C. This feature is a result of the aging effect of point defects/atoms rearrangement in B2 phase. Thermal cycling can also decrease transformation temperatures while increasing the hardness of the alloy. The strengthening effects of aging and thermal cycling on the Ms (M*) temperature of Ti40.5Ni49.5Zr10 alloy can be represented by the equation MS = To-K AΔσy. Experimental results indicate that martensitic transformation temperatures of Ti40.5Ni49.5Zr10 alloy can be more effectively depressed by aging than by thermal cycling.
Publisher
Elsevier Sequoia SA, Lausanne
Type
journal article