摘要
采用扫描电镜、光学显微镜和能谱仪等设备对AlSi7Mg铝合金激光选区熔化(SLM)成形试样经不同温度时效后组织形貌变化进行了研究。结果表明,SLM成形AlSi7Mg铝合金中有显微气孔存在,铺层面呈网状组织形貌,堆层面呈鱼鳞状组织形貌,共晶硅非常细小,呈点状或短棒状弥散分布。随时效温度的升高,其气孔率呈增大趋势,网状和鱼鳞状形貌逐渐模糊,直至消失,甚至出现树枝晶状形貌,而共晶硅长大并形成粗大的块状、针状形貌。时效温度低于300℃时,SLM成形AlSi7Mg铝合金超细晶结构中过饱和的Si、Mg元素沉淀析出,形成Mg_(2)Si强化相。时效温度高于300℃时,基体晶粒细化,细小共晶硅的网格状结构被破坏并开始聚集、长大,对基体的割裂作用增加。
Effect of aging temperature on microstructure of AlSi7Mg alloy formed by selective laser melting(SLM) was studied by means of scanning electron microscope(SEM),optical microscope(OM) and energy dispersive spectrometer(EDS).The results show that micro pinholes occure in the SLM formed AlSi7Mg alloy,as well as net-like microstructure in scanning direction and scale-like microstructure in building direction,meanwhile,punctiform and short rod-like eutectic Si is evenly distributed in Al matrix as particles.With the increase of aging temperature,the porosity increases,the net-like and scale-like microstructure gradually blur until disappeare,and even dendritic morphology appears,while the eutectic Si grows up,showing needle-like and bulk-like morphology.When the aging temperature is blow 300 ℃,the separated Si and Mg precipitate in the ultrafine-grained structure of the AlSi7Mg alloy,which form Mg_(2Si) strengthening phase.When the aging temperature is higher than 300 ℃,the grain of the AlSi7Mg alloy refines,the reticular eutectic Si are destroyed and grouped and grown,which increases the cleavage effect on Al matrix.
作者
刘松
Liu Song(AVIC Jincheng Nanjing Electrical and Hydraulic Engineering Research Center,Nanjing Jiangsu 211106,China)
出处
《金属热处理》
CAS
CSCD
北大核心
2023年第7期205-213,共9页
Heat Treatment of Metals
