Glass Forming Ability and Crystallization Behaviors of the Ti-Cu-Ni-(Sn) Alloys with Large Supercooled Liquid Region

摘要

The thermal stability and crystallization behavior of melt spun amorphous Ti_(50)Cu_(35)Ni_(15-x)Sn_x (x=0, 3, 5, 7) alloys has been studied in by thermal analysis (DSC and DTA) and X-ray diffractometry. Partial replacement of Ni by Sn up to 5 at % in Ti_(50)Cu_(35)Ni_(15) alloy improved thermal stability and glass forming ability. The onset temperature of the first exotherm increased from 739 to 756 K with increasing Sn content x from 0 to 5, and then decreased to 745 K for the alloy with x=7 due to change in crystallization sequence. Melt spun amorphous Ti_(50)Cu_(35)Ni_(12)Sn_3 and Ti_(50)Cu_(35)Ni_(10)Sn_5 alloys exhibit ΔT_x exceeding 78 and 76 K, respectively, which is significantly larger than ΔT_x of 46 K in Ti_(50)Cu_(35)Ni_(15) alloy. Amorphous Ti_(50)Cu_(35)Ni_(15) alloy crystallized by precipitation of supersaturated cubic Ti(Ni,Cu) phase followed by decomposition into a mixture of TiCu and TiNi at higher temperature. Amorphous Ti_(50)Cu_(35)Ni_(15-x)Sn_x (x=3, 5) phase crystallized by precipitation of cubic Ti(Ni,Cu) phase, followed by transformation into a mixture of TiNi, TiCu, Ti_3Sn phases. Amorphous Ti_(50)Cu_(32)Ni_8Sn_7 phase crystallized by co-precipitation of cubic Ti(Ni,Cu) phase and unidentified phase, followed by transformation into a mixture of TiNi, TiCu, Ti_3Sn phases.