激光焊接对块体非晶合金Zr_(45)Cu_(48)Al_7晶化行为的影响

Influence of laser welding on crystallization behaviour of Zr_(45)Cu_(48)Al_7 bulk metallic glass

采用激光焊接技术连接块体非晶合金Zr45Cu48Al7(摩尔分数,%)。结果表明:在焊接热循环作用下,熔化区和热影响区的晶粒形貌和组织具有很大的差异;焊接速率为2 m/min时,熔化区主要生成5τ(Zr38Cu36Al26)、ZrCu和一未知相,热影响区主要生成ZrCu相;焊接速率为4 m/min时,熔化区保持了非晶特性,热影响区部分晶化,其主要生成相为ZrCu相;热影响区的晶化行为与非晶合金热处理过程的晶化行为有一定的区别,其主要原因是激光焊接时的高速加热及冷却过程对各晶化相生长速率影响程度不同。

Using a laser welding method, two pieces of bulk metallic glasses （BMGs）based on Zr45 Cu48 Al7 （mole fraction, %） were welded. The results indicate that the morphology and the structure in heat-affected zones （HAZs） are different from those in molten zone. When the welding speed is 2 m/min, the majority of the crystalline phases in the molten zone are found to be r5 （Zr38 Cu36 Al26 ）, ZrCu and an unknown phase, those in the HAZs are mainly ZrCu phase. While the welding speed is 4 m/min, the molten zone keeps amorphous, HAZ is the discontinuous crystalline zone and the majority of the crystallites in HAZ are ZrCu phase. The crystallization behavior in HAZ is different from that of BMGs during heat-treating process, the main cause is that the effect on the growth speed of crystallization phases is different during the rapid heating and cooling process of laser welding.