Experimental Investigation Of Isothermal Section At 800K Of Mg-Sn-Ce Ternary System

In recent years,lightweight magnesium alloy is a hot topic in material research,but its poor high temperature properties hinder its development.The purpose of this work is to experimentally investigate the equilibrium phase diagram of the Mg-Sn-Ce ternary system at 800 K,which provides a theoretical basis for the development of magnesium alloy.The experimental points were selected through Hypothetical Test Method.The experimental samples were prepared by diffusion at high-temperature,and then being annealing at 800 K for30 days in the muffle furnace to reach equilibrium.The equilibrium samples were detected by X-ray diffraction（XRD）and electron scanning microscopy with band spectroscopy（SEM-EDX）.Through comprehensively analyzing the experimental data of XRD and SEM/EDX,and combining the phase diagram of boundary binary system,an isothermal section at 800 K of Mg-Sn-Ce ternary system was constructed.At 800 K,eight binary compounds were detected:Mg₂Sn of Mg-Sn binary system,Mg₁₂Ce,Mg₃Ce&MgCe of Mg-Ce binary system,and Ce₃Sn,αCe₅Sn₃,Ce₅Sn₄&Ce Sn₃of Sn-Ce binary system.The maximum solubility of Mg inCe Sn₃,αCe₅Sn₃,Ce₅Sn₄and Ce₃Sn are about 13.2,3.5,11.1 and 2.7 at.%,respectively;the solubility of Sn in Mg₁₂Ce,Mg₃Ce and MgCe are about 0.3,1.0and 4.5 at.%,respectively;and the solubility of Ce in Mg₂Sn are about 0.5 at.%.In addition,three ternary compounds:τ₁（MgSnCe）,τ₂（MgSn₂Ce）andτ₃(Mg₂₃SnCe₆),were confirmed existing at 800 K.Two new ternary compounds:τ₄(Mg_44.7Sn_36.4Ce_18.9)andτ₅(Mg₄₀Sn₂₄Ce₃₆),were found in this work.Through indexing diffraction lines ofτ₄andτ₅,theτ₄(Mg_44.7Sn_36.4Ce_18.9)was identified to be a hexagonal system with lattice parameters a=8.327（?）,c=14.939（?）;theτ₅(Mg₄₀Sn₂₄Ce₃₆)is identified to be a hexagonal system with lattice parameters a=7.711（?）、c=4.833（?）.