摘要
采用超音速气体雾化设备制备AlSi7MgTi合金粉末,利用激光选区熔化技术将其制成试块,并进行T6热处理。利用光学显微镜、扫描电子显微镜、X射线衍射仪、拉曼光谱仪和拉伸实验研究成形态与T6态合金的显微组织、相组成、残余应力和力学性能。结果表明:成形态合金由过饱和α(Al)固溶体和Si相组成,组织形貌呈现出“鱼鳞状”熔池逐层堆叠和相互交织的特征,并表现出明显的各向异性。此外,Si相以网状共晶硅的形式存在,由块状和纤维状的共晶硅相互连接而成。熔池边界附近的共晶硅相对粗大,熔池内部的则较为细小。T6热处理促使合金中Si相析出,导致共晶硅发生Ostwald粗化,基本消除了熔池形貌和网状共晶硅组织,并使残余应力显著降低。成形态合金的抗拉强度与屈服强度分别达到420~430 MPa和280~300 MPa,伸长率为5.1%~11.0%;T6热处理后合金的抗拉强度降至360 MPa左右,屈服强度与成形态相当,伸长率提升至15.2%~16.5%。
The testing blocks of AlSi7MgTi alloy were prepared by selective laser melting(SLM)technique and T6 heat treatment using alloy powders fabricated by supersonic gas atomization equipment.The microstructure,phase composition,residual stress,and mechanical properties of as-built and T6 treated alloys were investigated by optical microscope,scanning electron microscope,X-ray diffractometer,Raman spectrometer and tensile tests,respectively.The results indicate that as-built alloy mainly consists of supersaturatedα(Al)solid solution and Si phases.The microstructure characterized by layer-by-layer stacking and interlaced of“scale-like”melt pool,shows obvious anisotropy.In addition,Si phase exists in the form of cellular eutectic silicon,which is connected by blocky and fibrous eutectic silicon.The eutectic silicon near melt pool boundary is relatively thick,while it is smaller in interior of melt pool.T6 heat treatment promotes the precipitation of Si phases,and leads to the Ostwald coarsening of eutectic silicon.Meanwhile,the melt pool morphologies and cellular eutectic silicon structure are basically eliminated by T6 heat treatment.Additionally,the residual stress is significantly reduced after heat treatment.The tensile strength and yield strength of as-built alloy reach up to 420-430 MPa and 280-300 MPa respectively,with elongation of 5.1%-11.0%.However,the tensile strength of T6 heat treated alloy is reduced to about 360 MPa,and yield strength is almost equal to that of as-built alloy,while elongation increases to 15.2%-16.5%.
作者
唐鹏钧
房立家
杨斌
陈冰清
李沛勇
张学军
TANG Peng-jun;FANG Li-jia;YANG Bin;CHEN Bing-qing;LI Pei-yong;ZHANG Xue-jun(AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China;Beijing Engineering Research Center of Advanced Aluminum Alloys and Applications,Beijing 100095,China;HFYC(Zhenjiang)Additive Manufacturing Co.,Ltd.,Zhenjiang 212132,Jiangsu,China)
出处
《材料工程》
EI
CAS
CSCD
北大核心
2020年第11期116-123,共8页
Journal of Materials Engineering
