Superhigh Yield Ratio and Considerable Plasticity in Powder Metallurgy Al-Zn-Mg-Cu Alloy Prepared with Elemental Powder

The present work investigated an Al-4.5Zn-2.9Mg-0.25Cu (wt.%) alloy with superhigh yield ratio and favorable plasticity prepared by an improved powder metallurgy (PM) technique, including elemental powder mixing compared with ball milling, cold isostatic pressing, vacuum sintering and hot extrusion followed by T6 heat treatment. Microstructure evolution in different processes was characterized by optical microscopy, scanning electron microscopy, energy dispersive spectrometry and electron backscattered diffraction. Tensile properties were measured at room temperature. The results show that the sample fabricated by mixed elemental powder has comparatively excellent mechanical properties. The ultimate tensile strength (UTS), yield strength (YS) and elongation (EL) of the corresponding sample after T6 heat treatment come up to 527 MPa, 512 MPa and 11.5%, respectively, with high yield ratio of 0.97, very close to the sample using ball-milled powder (547 MPa UTS, 514 MPa YS, 11% EL, 0.94 yield ratio). Fine grains and Al₂O₃ nanoparticles in PM aluminum alloys in this study are distinguished from other aluminum alloys, which contribute to the enhancement of mechanical properties. This provides a novel strategy for the simple and efficient preparation of high-performance powder metallurgy aluminum alloy.