铜基大块非晶合金的临界冷速与组织形貌变化

Critical Cooling Rate and Microstructure Evolution of Cu-Based Bulk Amorphous Alloy

摘要:

制备了具有良好玻璃形成能力的Cu52.5Ti30Zr11.5Ni6大块非晶合金，其临界直径达到5mm，临界冷却速率约为126．8K／s。采用Jackson-Hunt公式计算了晶化组织形成的冷却速率。当冷却速率在10K／s-120K／s时，晶化组织则出现亚稳初生相与共晶共存的形态。当冷却速率低于10K／s时，亚稳初生相的析出将被逐渐抑制，使得共晶生长方式发生改变。

Abstract:

Bulk amorphous Cu52.5Ti30Zr11.5Ni6(at.%) alloys up to 5 mm in diameter were fabricated by a copper mold casting method.The critical cooling rate was determined to be 126.8 K/s by using the Barandiaran-Colmenero expression.Based upon the Jackson-Hunt relation,the cooling rate for the formation of devitrified structure was also evaluated.In the cooling range of 10 K/s ~ 120 K/s,there exists a mixed microstructure of primary metastable phase and eutectic structure.With further decreasing of cooling rate(below 10K/s),the precipitation of metastable phase was depressed,and the growth mode also deviates from the eutectic mode.