Study On Aging Properties And Microstructure Of Au-14Cu-9Pt-4Ag-0.5M Alloy

As modern society advances in the field of aviation, spaceflight, navigation,etc., the new material of precious metals have greatly developed.Precious metals and their alloys have excellent chemical stability,good thermal conductivity and electrical conductivity,so that are widely applied in the field of electric contact.In this paper,the AuCuPtAgM alloy was prepared by means of wire processing technology,the microstructure evolution and mechanical properties are studied by scanning electron microscopy(SEM),X-ray diffraction(XRD),electronic universal testing machine,etc.,the main research results are as follow:(1)Aging temperature had obvious effects on increasing the hardness and tensile strength of AuCuPtAgM alloy,it improved hardness to 351HVo.i and tensile strength to 1327MPa or more,there is a maximum range of hardness aging temperature (325～400℃),with benifit to control aging hardness of the alloy;(2)After isothermal aging at 325℃ for 0.5h,the hardness and tensile strength of AuCuPtAgM alloy quickly improved to the maximum and then decreased,and stabilized;(3)The resistivity of aging alloy decreased quickly with the increase of aging temperature and aging time.Aging temperature can fast drop the resistivity value to 15.32μΩ·cm,it droped to 33%,but to 15.6% for aging time;(4)The phase of AuCuPtAgM alloy after quenching is the Au-based solid solution with face-centered cubic structures(FCC) and it’s microstructure is equiaxed grains.There are AuCu ordered phase transformation and AuCu ordered phase transformation during aging,the ordering transformation start temperature of Au3Cu ordered phase is 257.0℃, and it of AuCu ordered phase is 325.9℃;(5)The effect of different aging temperature and aging time on the ordered phase transformation and microstructure of AuCuPtAgM alloy were studied,the results that:1)The ordered phase transformation accelarated from Au-based solid solution to ordered phase when aging temperature and aging time increase,and with the content of Au3Cu ordered phase increased,the equiaxial crystal size of alloy decreased,finally,the equiaxial grains disappear and formed two-phase hybrid structure of Au3Cu ordered phase and AuCu ordered phase;2)with the AuCu ordered phase precipitated and increased,there are large particles precipitated in the alloy,which had more content of M than alloy combined EDS energy spectrum analysis,it illustrated that addition of M element can promote the transformation of Au3Cu to AuCu.