A study on martensitic transformation in Ti50−x/2Ni50−x/2Cux alloys with X≤10 at%

Abstract

The effect of Cu additions on the martensitic transformation sequence and temperature in Ti50−x/2Ni50−x/2Cuxalloys with x: 1–10 at% are investigated by ER, DSC, X-ray and IF measurements. Experimental results show that the transformation sequence of Ti50−x/2Ni50−x/2Cux alloys with x: 1–4 at% proceeding as two-stage B2→R→B19′ transformation on cooling and Ti50−x/2Ni50−x/2Cux alloys with x=5, 10 at% have no martensitic transformation. The addition of Cu in Ti50−x/2Ni50−x/2Cux alloys assists the formation of R-phase, a behaviour which is quite different from that in Ti50Ni50−xCux alloys. Both the Ms and T R temperatures decrease rapidly with increasing Cu addition in Ti50−x/2Ni50−x/2Cux alloys with x: 1–4 at%. It is proposed that the Cu+Ni effects on the Ms temperature in Ti50−x/2Ni50−x/2Cux alloys is similar as Cu +Ni effects in Ti50Ni50−xCux alloys and as Ni effects in as-quenched Ni-rich TiNi alloys.