Research On Preparation And Forming Of In-situ Mg₂Si/AM60Composites With Ultrasonic

In this paper,Mg2Si/AM60composites was prepared by combined melt direct reaction method with ultrasonic treatment. Effect of ultrasonic treatment process which included ultrasonic treatment time and ultrasonic treatment power on action effect of Mg2Si/AM60composites were investigated. The results show that the morphology of Mg17Al12phases exhibit the change from semi-continuous net-structur into granular shape with increasing ultrasonic treatment time or ultrasonic treatment power, and coarser chinese-script Mg2Si phases become finer chinese-script、fibrous and granular shape.Meanwhile,mechanical properties of in-situ Mg2Si/AM60composites improve gradually,but it will decrease with ultrasonic treatment time of more than60s. Ultrasonic treatment of600W for60s,there exists the well-distributed granular shape Mg2Si phases and Mg17Al12phases which are significant inhibited.Meanwhile,the tensile strength and elongation of in-situ Mg2Si/AM60composites are increased to196.75MPa and5.28%, increased by10.4%and48.3%compared with178.24MPa and3.56%of one without ultrasonic treatment.Effect of trace B2O3on in-situ Mg2Si/AM60composites was investigated. Meanwhile,mechanism of B2O3was analysised. Microstructures of in-situ Mg2Si/AM60composites experience a process of refinement firstly,and then grown with increasing the content of B2O3from0.20Wt%to0.60Wt%.It is better when the content of B2O3is0.40Wt%.The grain size exhibits the change from140μm reduced into50μm or so. Semi-continuous net-structur Mg17Al12phases become granular shape,and coarser chinese-script Mg2Si phases become fibrous and granular shape.Mg17Al12and Mg2Si phase of in-situ Mg2Si/AM60composites become granular shape and uniform by combined0.40Wt%B2O3with ultrasonic treatment of600W power for60s.Semi-solid in-situ Mg2Si/AM60composites slurry was prepared by ultrasonic vibration. Effect of ultrasonic vibration process which included ultrasonic leading-in temperature、ultrasonic vibration time and ultrasonic vibration power on morphology、 composition and distribution of primary α-Mg particles of semi-solid in-situ Mg2Si/AM60composites slurry were investigated. The results show that primary α-Mg particles mostly become near-spherical shape after transitory ultrasonic vibration. Near-spherical shape of primary α-Mg particles gradually turn fine、uniform and increase the amount by reducing ultrasonic leading-in temperature and increasing ultrasonic vibration time or ultrasonic vibration power,but its morphology will decrease and grow with ultrasonic leading-in temperature of lower than620℃or ultrasonic vibration time of more than90s.Under the condition of appropriate parameters:ultrasonic vibration of600W for90s from620℃leading-in,microstructures of semi-solid in-situ Mg2Si/AM60composites slurry become fine and uniform. Primary α-Mg particles become near-spherical shape, and its grain size fasten on50μm to80μm.Finally,filling process of liquid and semi-solid of the new material were simulated by Flow-3d. Forming of cover part was experimented by self-design die.