Effect of Forging Temperature on the Microstructure, Subsequent Aging Precipitation Behavior, and Mechanical Properties of Mg-Gd-Y-Zr-Ag Alloy

The deformation mechanism,microstructure evolution,and precipitation behavior of a Mg-8.9Gd-1.8Y-0.5Zr-0.2Ag(wt.％)alloy multi-directionally forged at three different temperatures were investigated.As the forging temperature increases,the particle-stimulated nucleation(PSN)effect diminishes as the num-ber of dynamic precipitates decreases,pyramidal slip is activated,grain boundary migration accelerates,and continuous dynamic recrystallization(CDRX)dominates.The microstructures varied greatly,although fine-grained structures were formed at all different forging temperatures.Competitive precipitation be-tween dynamic precipitate growth,dislocation-induced precipitation,and homogeneous precipitation was observed after aging treatment.Among them,the medium temperature(748 K)forged and aged alloy ex-hibits the best mechanical performance,with an ultimate tensile strength of 436 MPa,and elongation of 16.3％.The calculation indicates that the mixed precipitation structure containing the β'precipitate band provides a 35％higher strengthening contribution than the typical homogeneously distributed precipi-tates.The formation of precipitation-free zones(PFZs)ensures that aging will not cause a dramatic de-crease in ductility,which provides a reference for the industrial preparation of high-performance wrought Mg-Gd series alloys.