The Study Of Microstructure And Properties Of Al-Si High Thermal Conductivity Alloy

In recent years,cooling of electronic products has become the focus of attention,Al-Si alloy heat sink material has good market prospects,and the requirements for improving the mechanical properties and thermal conductivity of aluminum-silicon alloy is growing.In this study,firstly,the phase composition and thermal conductivity of Al-8%Si alloy with Cu,Mg,Zn,Fe,Mn and Zr was calculated and simulated.Secondly,the lows of mechanical properties and thermal conductivity that alloying elements Cu,Mg,Zn,Fe,Mn and Zr and metamorphism influence on Al-8%Si alloy are studied by the mechanical properties test,conductivity test and observation of the organization.In to Al-8%Si-(0.5%?2.8%)Cu alloy,the tensile strength is improving with the increase of Cu content,while the thermal conductivity is reducing with the increase of Cu content.After the alloy aging,when the content of Cu is 0.5%,the alloy tensile strength and thermal conductivity is 161.3MPa and 153.2 W/m·K;when the content of Cu is 2.8%,the alloy tensile strength and thermal conductivity is 290.4MPa and 131.9 K W/m.In the Al-8%Si-3%Cu alloy,adding 0.3%Mg and 0.2%Zn can reduce thick flake eutectic silicon,refine the fibrous eutectic silicon,and Al-8%Si-3%Cu will be reinforced,while it influence slightly on thermal conductivity of alloy;Adding 0.14%Mn and 0.5%Fe can reduce thick flake eutectic silicon,and thermal conductivity and tensile strength decrease slightly.In the Al-8%Si-0.8%Mg alloy,the thermal conductivity is decreasing with the increase of Cu content(0.1%?0.5%),the tensile strength is improving with the increase of Cu content(0.1%?0.5%);the Zn content(0.1%?0.5%)influence slightly on the thermal conductivity,and Zn have a poor effect on reinforcement for alloy.When the content of Cu is 0.5%,the Al-8%Si-0.8%Mg alloy achieve a well comprehensive performance after aging,the thermal conductivity,tensile strength and hardness is 166.0 W/m·K,294.0 MPa and 101.3 HV respectively.In the Al-8%Si-0.8%Mg-0.5%Cu alloy,Fe content from 0.14%to 0.17%,adding a certain Mn content of 0.08%,0.16%and 0.24%respectively.With the Mn content increasing,the thermal conductivity reduces rapidly in the beginning,followed with a slow trend of reduction,tensile strength improve rapidly in the beginning,followed with a slow trend of increase.The hardness is improving with the increase of Mn content.In the cast alloy,Mn can reduce the thick needle-shaped and flake iron-bearing phases,adding 0.08%Zr can reduce the tensile strength and thermal conductivity.The high Fe content(up to 0.4%)influences the tensile strength and thermal conductivity slightly.In Al-8%Si-0.8%Mg-0.5%Cu alloy,thermal conductivity and hardness of the alloy are changed due to change of the solution and aging treatment conditions.Solution temperature from 480? to 540? thermal conductivity reduce with solution temperature increasing,the hardness improve with the increase of solution temperature.The hardness of alloy achieves the maximum at the solution time of 4h under 520 ?.The temperature of aging from 180?to 240?,with aging temperature increasing,the thermal conductivity improves,while the hardness decreases;With the aging time increasing,the thermal conductivity improves,while the hardness achieves the maximum at 2h.