The Study Of Casting Magnesium Alloy GYZ103 With High Strength And Heat Resistance

According to the performance demands of high-strength heat-resistant magnesium alloy,identify the alloy compositions by optimizing the Mg-Gd-Y-Zr alloy.The range is:10%～11%Gd,2.5%～3.5%Y,0.4%～0.6%Zr.Comparing the Mg-Gd-Y-Zr alloy adopted low-temperature and high-temperature melt,it is found that high-temperature melt increases effective yields of Gd,Y slightly and Zr greatly,but also refines the grain.In addition,the paper optimizes the heat treatment processing by proceeding orthogonal test of the solution temperature,solution time,aging temperature and aging time of GYZ103 magnesium alloy.By observing the microscopic structure it is found that after 500℃+ 8h solution treatment,the GYZ103 alloys solid fully and the grain happens no growth.But the overaging phenomenon occurrs after the temperature increase or the solution time extend.In the subsequent 250℃aging treatment,the shape of precipitate phases change in different aging time:small amount of petal-like + small amount of small granular→hunk petal-like+large number of small granular→small amount of petal- like+coarse granular→coarse granular.By analyzing the petal-like and granular organizations of GYZ103 alloy it found that after 250℃+24h aging treatment,the petals are composed of two phases,one is Zr-rich phase in the center of a petal,the other is slender needle-like phase;and the granular organizations are composed of rich Gd,Y phase.So ascertain the heat treatment process of GYZ103 magnesium alloy as 500℃×8h+250℃×24h.Adopt this technology the mechanical properties of the GYZ103 magnesium alloy reach:tensile strength 377MPa,yield strength 333MPa and elongation 5%at room-temperature and 210MPa,175MPa and 17%at 300℃.