The effects of cooling rates corresponding to different diameters of the steel mould and laser surface melting(LSM)on the as-cast microstructures of Mg-9Al-xSi(x=1,3)(mass fraction,%)alloys were investigated by XRD an...The effects of cooling rates corresponding to different diameters of the steel mould and laser surface melting(LSM)on the as-cast microstructures of Mg-9Al-xSi(x=1,3)(mass fraction,%)alloys were investigated by XRD and OM.The results show that obvious refinement of the alloy microstructure is obtained with increasing cooling rate by conventional ingot metallurgy.However, no evident modified morphologies of both dendritic primary Mg2Si and Chinese script eutectic Mg2Si in the Mg-Al-Si alloy occurs. Surprisingly,the morphologies of Mg2Si phases within the laser-melted Mg-Al-Si alloy transform drastically from both coarse Chinese script shape for the eutectic Mg2Si and dendrite for the primary Mg2Si to fine spherical particles with an average size of about 3μm due to the rapid cooling of the melted layer,and the Mg2Si particulates distribute more uniformly in theα-Mg matrix.展开更多
A dry mechanical surface treatment was described, in which irregularly shaped metal powders were impacted and sphericized by using high speed airflow impact method particles composite system(PCS). The optimum technolo...A dry mechanical surface treatment was described, in which irregularly shaped metal powders were impacted and sphericized by using high speed airflow impact method particles composite system(PCS). The optimum technological parameters for the metal powders processed were determined according to the treatment effect under different conditions. The results show that the irregularly shaped metal powders are impacted into dense spherical particles, the bulk density and tap density of the metal powders increase noticeably. The combination property of metal powders is improved greatly.展开更多
基金Project(LRB05-311)supported by the Postdoctoral Foundation of Heilongjiang Province,ChinaProject(HEUFT05038)supported by the Basic Research Foundation of Harbin Engineering University,ChinaProject(2009AA03Z423)supported by the National High-TechResearch and Development Program of China
文摘The effects of cooling rates corresponding to different diameters of the steel mould and laser surface melting(LSM)on the as-cast microstructures of Mg-9Al-xSi(x=1,3)(mass fraction,%)alloys were investigated by XRD and OM.The results show that obvious refinement of the alloy microstructure is obtained with increasing cooling rate by conventional ingot metallurgy.However, no evident modified morphologies of both dendritic primary Mg2Si and Chinese script eutectic Mg2Si in the Mg-Al-Si alloy occurs. Surprisingly,the morphologies of Mg2Si phases within the laser-melted Mg-Al-Si alloy transform drastically from both coarse Chinese script shape for the eutectic Mg2Si and dendrite for the primary Mg2Si to fine spherical particles with an average size of about 3μm due to the rapid cooling of the melted layer,and the Mg2Si particulates distribute more uniformly in theα-Mg matrix.
基金Project(50474003) supported by the National Natural Science Foundation of China
文摘A dry mechanical surface treatment was described, in which irregularly shaped metal powders were impacted and sphericized by using high speed airflow impact method particles composite system(PCS). The optimum technological parameters for the metal powders processed were determined according to the treatment effect under different conditions. The results show that the irregularly shaped metal powders are impacted into dense spherical particles, the bulk density and tap density of the metal powders increase noticeably. The combination property of metal powders is improved greatly.
