Effect Of Sn/Cu On Thermal Conductivity And Mechanical Properties Of Magnesium Alloy

Many fields need more requirement of alloy that have high thermal conductivity today.Improving the thermal conductivity and losing material's weight gradually become hot spot of research.Magnesium alloy has great advantages in losing material's weight,and it has high thermal conductivity,making it be valuable in study.So it is necessary to produce a kind of magnesium alloy that has high thermal conductivity and satisfactory mechanical properties.The microstructure,thermal conductivity and mechanical properties of the as-cast Mg-xSn?x = 1,3,5,7,9?alloy,the as-cast Mg-3S_n-xCu?x= 0.5,1,2,3?alloy and the as-aged Mg-3S_n-1Cu alloy were investigated by optical microscope?OM?,scanning electron microscope?SEM?,X-ray diffraction?XRD?analysis tools and some instruments about testing thermal conductivity and mechanical properties,the results show that:Moderate Sn could make the grain refined dramaticlly.When Sn content is5%,the grain size is smallest.The Mg₂ Sn phase precipitates along the grain boundaries with the increase of Sn content,and gradually form the reticular structures and then coarse.The thermal conductivity decreases with the addition of Sn content.The maximum value of thermal conductivity is 141.58 W/m·K when Sn content is 1%.The tensile strength and elongation rise with the increase of Sn content.When Sn content is 5%,they have the maximum values of 150.23 MPa and 8.7% respectively.The tensile strength and elongation descend while Sn content is greater than 5%.The hardness of Mg-xSn alloy rise with the increase of Sn content.With the increasing of Cu,the grain of Mg-3Sn-x Cu alloy is refined dramaticlly and there are a large number of Mg₂ Cu and Mg₂ Sn phase precipitating along the grain boundaries and gradually forming the reticular structures and then coarsing.The thermal conductivity was increased with the addition of Cu content.When Cu content is 3%,the thermal conductivity reachesthe highest value of 107.03 W/m·K.The tensile strength and elongation rise with Cu content increased first,and then decrease while Cu content is greater than 1%.When the content of Cu is 1%,the tensile strength and elongation have the maximum values of 167.10 MPa and 11.37% respectively.The hardness increase first and then decrease with the increasing of Cu content,and the hardness is the largest when the content of Cu is 2%,the value was 54.5 HB.After aging treatment,the grain of Mg-3S_n-1Cu alloy is mainly composed of equiaxial crystal grains.Mg₂ Sn phase and Mg₂ Cu phase precipitate dispersively from grain boundaries and grain inside.With the increasing of aging time,Mg₂ Sn phase and Mg₂ Cu phase gradually grow up.The thermal conductivity increases with the aging time increasing from 95.34 W/m·K to 120.60W/m·K.The tensile strength first increases and then decreases slowly with the aging time increasing,reaching the aging peak value of 189.05 MPa at aging 36 h.The elongation decreases with the aging time increasing.The hardness shows a downward trend after the first rising.The peak value of hardness is 53.6 HB at aging 36 h.