Abstract
In this work,the A356/AZ91D bimetal composites were prepared by ultrasonic vibration-assisted lost foam compound casting,and the effects of ultrasonic powers on interfacial microstructures and mechan-ical properties of the Al/Mg interfaces were investigated.Results revealed that the Al/Mg bimetal com-posites without ultrasonic vibration treatment(UVT)were heterogeneous,and the Al/Mg interface was composed of Al-Mg intermetallic compounds(IMCs,i.e.,Al3Mg2 and Al12Mg17)area and Al-Mg eutec-tic structures(δ-Mg+Al12Mg17)area.The Mg2Si particles were gathered at the IMCs area and an oxide film that mainly composed of Al2O3 was existed between the IMCs area and eutectic structures area.With UVT,the oxide film was eliminated and the gathered Mg2Si particles were refined and dispersed by the acoustic cavitation effect,and part of the Al3Mg2 and Al-Mg eutectic structures were transformed into the Al12Mg17 due to the promoted solute interdiffusion,which improved the homogeneity of the Al/Mg interfaces.Besides,the grains of the Al/Mg interface with UVT under ultrasonic power of 75 W were significantly refined.The thickness of Al/Mg interface was increased with the increase of the ul-trasonic power.Due to the excessive heat induced by UVT under the further increased ultrasonic power,the cooling rates and the degree of supercooling were reduced,resulting in the coarsening of interfacial grains.The microhardness of the Al/Mg interfaces was increased and got more uniform by UVT.The shear strengths of the Al/Mg bimetal composites with UVT were enhanced to 61.4 MPa from 32.4 MPa,with an increase of 89.5％compared with that of the Al/Mg bimetal without UVT.This could be ascribed to the removal of the oxide film,the refinement of the interfacial grains and the dispersed and refined Mg2Si particles achieved by UVT,which hindered the crack propagation during deformation.
基金项目
National Natural Science Foundation of China(52271102)
National Natural Science Foundation of China(52075198)
National Key Research and Development Program of China(2020YFB2008304)
Analytical and Testing Center,HUST()
NETL
NSTL
万方数据