Microstructural evolution,dislocation density and tensile properties of Al–6.5Si–2.1Cu–0.35Mg alloy produced by different casting processes  

作　　者：S.Samat M.Z.Omar A.H.Baghdadi I.F.Mohamed A.Rajabi A.M.Aziz 

机构地区：[1]Department of Mechanical and Manufacturing Engineering,Faculty of Engineering and Built Environment,Universiti Kebangsaan Malaysia,Bangi,UKM 43600,Malaysia

出　　处：《Journal of Materials Science & Technology》2021年第36期145-157,共13页材料科学技术（英文版）

基　　金：financially supported by the Universiti Kebangsaan Malaysia and the Ministry of Education(MoE)Malaysia(Nos.MI-2019-025 and DIP-2016-007)。

摘　　要：Al–Si–Cu–Mg foundry alloys are used in casting process technologies.However,their strength properties remain low due to their microstructural characteristics and porosity.In this work,the microstructural characteristics,dislocation densities,and mechanical properties of Al–Si–Cu–Mg cast alloys prepared through different casting methods were studied experimentally.Four casting processes,namely,gravity casting(GC),rheocasting(RC),thixoforming(Thixo),and Thixo with heat treatment,were used.The GC and RC samples had mainly dendriticα-Al phase microstructures and exhibited coarse Si particles and intermetallic compounds in their interdendritic regions.By contrast,the Thixo and heat-treated Thixo(HT-Thixo)samples exhibited microstructural refinement with uniformly distributedα-Al globules,fine fibrous Si particles,and fragmented intermetallic compounds amongα-Al globules.The accumulation of dislocation densities increased in the Thixo sample as the strain was increased due to plastic deformation.Furthermore,the ultimate tensile strength and yield strength of the HT-Thixo sample increased by 87%and 63%,respectively,relative to those of the GC sample.The cleavage fracture displayed by the GC and RC samples led to brittle failure.Meanwhile,the Thixo and HT-Thixo samples presented dimple-based ductile fracture.

关 键 词：Al–Si–Cu–Mg alloy THIXOFORMING Microstructure Mechanical property Dislocation density 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG292[金属学及工艺—金属材料]