脉冲频率对脉冲激光重熔Zr_(55)Cu_30Al_(10)Ni_5块体非晶合金晶化行为的影响  

Effect of Pulsed Laser Frequency on Crystallization during Laser Remelting Zr_(55)Cu_30Al_(10)Ni_5 Metallic Glass

作　　者：杨高林[1] 林鑫[1] 胡桥[1] 张莹[1] 黄卫东[1] 

机构地区：[1]西北工业大学凝固技术国家重点实验室,陕西西安710072

出　　处：《应用激光》2013年第3期225-232,共8页Applied Laser

基　　金：国家重点基础研究发展计划(973)资助项目(项目编号:2011CB610402);高等学校博士学科点专项科研基金资助项目(项目编号:20116102110016);国家高技术研究发展计划(863)资助项目(项目编号:2013AA031103);高等学校学科创新引智计划资助项目(项目编号:08040)

摘　　要：采用脉冲激光重熔Zr55Cu30Al10Ni5块体非晶合金,研究了脉冲激光频率对激光重熔块体非晶合金晶化行为的影响。实验结果表明,对于给定的能量密度,在脉冲频率低于一临界值时,脉冲频率对晶化几乎没有影响。反之,晶化程度随脉冲频率的增加迅速增加。采用有限元方法模拟了激光重熔非晶合金的温度场,发现过高的脉冲激光频率会产生热累积效应,进而对激光熔池热影响区的晶化行为产生重要影响。其中,热累积效应的影响分为两种,第一种是由于脉冲激光频率过高时,受合金自身热扩散能力所限,前后两个脉冲激光重熔所引起的熔池局域高温区发生重叠,进而引起熔池局域过热。这种热累积效应只能靠降低频率来避免。第二种是试样周围的散热条件差,在激光加工时使得材料整体升温而降低了冷却速度。这种热累积效应可以靠加强材料周围的散热来抑制。The Zr55Cu30Al10Ni5 metallic glass was remelted by pulsed laser to research the effect of frequency of pulsed laser on crystallization during laser remelting. The result shows that, when the frequency is lower than a certain value, the crystallization is independent on the laser frequency. When the frequency is high enough, the crystallization will increase with the increase of the frequency. There are two aspects of frequency to impact on the crystallization. The first aspect is the localization of the temperature field caused by laser remelting which make the molten pools of adjacency laser irradiations added together. This kind of heat accumulation can be avoided only by reducing the frequency. The second aspect is caused by the poor cooling condition around the specimen which makes the whole specimen heating up.

关 键 词：激光技术 非晶合金 激光频率 热累积 

分 类 号：TN249[电子电信—物理电子学]