The Preparation Process And Microstructure And Properties Of Al₂O_3f/Mg-6Al-0.5Nd-1Gd Magnesium Matrix Composites

With the energy crisis and environmental pollution problems in the world becoming more and more serious,the use of magnesium alloy instead of automotive Aluminum Alloy even steel materials to reduce the car's own weight and the energy consumption has become an inevitable trend.Magnesium alloy has high strength and specific stiffiiess.It is the lightest metal material in common engineering materials at present.While adding rare earth elements and reinforced,the Al2O3f/Mg-6Al-0.5Nd-1Gd composite material has higher temperature and mechanical properties than the general magnesium alloy.So the Al2O3f/Mg-6Al-0.5Nd-1Gd composite material has wide application prospect in the automotive,aerospace and other fields.In the paper,Al2O3f/Mg-6Al-0.5Nd-1Gd composite was prepared by using the method of pressureless Infiltration process,and densification treatment was carried out on it at Semi-solid temperature?The effect of Nd and Gd on the.microstructure,phase composition,hardness and high temperature compression property were analyzed by OM,SEM,XRD and EDS.The friction and wear properties of the composite ware measured.The effect of temperature on Al2O3f/Mg-6Al-0.5Nd-1Gd composite was analyzed.The main conclusions are demonstrated as follows:(1)Al2O3f have no obvious orientation after densification treatment.The matrix is compact,without micro pores.At the same time,the morphology of a-Mg phase changes from arborization to short spherical.(2)The addition of rare earth elements Gd and Nd not only makes the composite materials significantly refined,also can make the ?-Mg17Al12 phase fine and dispersed.Adding rare earth elements results in the formation of the high melting point of Al2Nd phase and Al2Gd phase,which make the Mg2Si phase to change from the large multilateral shape into a small short rod and punctate distribution in grain boundaries.The hardness of the composites was increased by 70.1%.(3)The high temperature compressive strength of Mg-6A1 alloy and Al2O3/Mg-6Al-0.5Nd-1Gd composite material was decreased with increasing temperature at the constant s train rate.The compressive strength of the alloys was decreased from 295.4 MPa to 103.3MPa.The compressive strength of the composites decreased from 382.1MPa to 152.8MPa.At the same temperature,the compressive strength of Al2O3f/Mg-6Al-0.5Nd-1Gd c omposites is higher than that of Mg-6Al alloys,and the amount of that is over 28%.(4)Under the condition of room temperature(25?),the friction coefficient and the wear rate was increased with the increasing of load.When the load are respectively 100N,150N and 200N,the friction coefficient are respectively 0.06,0.11 and 0.15,and the wear rate were 0.058 g/h,0.077g/h and 0.155g/h.The failure form of the composite is dominated by abrasive wear.At high temperature(250?)condition,the friction coefficient and wear rate also showed similar to the room temperature trend.When the load are respectively 100N,150N and 200N,the friction coefficient are respectively 0.16,0.18 and 0.36,and the wear rate are 0.16g/h,0.24g/h and 0.20g/h respectively.Adhesive wear is the main failure mode of the composites.