Study On Preparation Of Al-Ce Master Alloy And Its Effection On A356 Alloy

In this paper,the Al-Ce master alloy(Al-Ce MA)prepared by pure aluminum and rare metal Ce.With the OM,SEM,EDS,XRD,ICP,we studied the effect of melting temperature and protective measures on the microstructure and actual yields of Al-Ce MA,we also studied the effect of Al-Ce MA on A356 alloy.The results show that when the melting temperature is 720? and protective measures are added,the maximum actual yield of Ce is 90%.Al-Ce MA consists of ?-Al,Al11Ce3,and Ce phase.Al11Ce3 formed by eutectic reaction in preparation of Al-Ce MA,which is bright white on the ?-Al matrix.The effects of different additions of Al-Ce MA on the microstructure and properties of A356 alloy were studied.The results show that ?-Al and eutectic Si of A356 alloy decrease first and then increase with the increase of Al-Ce MA additions.The hardness,tensile strength,elongation and corrosion resistance increase first and then decrease with the increase of Al-Ce MA additions.The best properties were achieved at amount of 0.1% Al-Ce MA,the ?-Al grain diameter of A356 alloy is 24.5?m,which is 80.5% lower than that of non-additive;The secondary dendrite arm spacing(SDAS)is 14.63?m,the decrease is 40.5%;the size of the Si phase is 7.4?m,the drop is 76.1%;the hardness is 77.6HV,the increase is 7.8%;the tensile strength and elongation are 165.89 MPa and 3.5%,Respectively,increased by 38.1% and 44%;weight loss rate of 0.7865 × 10-4g /(cm2 * h),about non-additive weight loss rate of half.The mechanism is analyzed as follows: Al11Ce3 formed by eutectic reaction in preparation of Al-Ce MA has the similar crystal structure and lattice constant with ?-Al,so it will be the heterogeneous nucleation sites when ?-Al begins solidification.