IMS: Effect of pretreatment on microstructural stability and mechanical property in a spray formed Al-Zn-Mg-Cu alloy

Aluminum alloys fabricated by spray forming (SF) technology are commonly followed by hot-working without heat treatments. A new approach that is a pretreatment before hot-working is proposed in the present work. The results show that the microstructural stability of materials processed by this new approach is improved evidently, which is related to the pinning effect on dislocations and grain boundaries by Al₃Zr particles induced during pretreatment. The strength of SF Al alloy processed by this treatment can be enhanced significantly. Owing to the combined effect of grain refinement strengthening, dislocation strengthening and precipitation strengthening, the yield strength and ultimate tensile strength can be enhanced by 171 MPa and 143 MPa, respectively. Based on experimental characterizations and a physical-based model, the underlying mechanisms regarding on enhancement of mechanical properties is mainly related to the induced Al₃Zr particles and the optimized precipitates by the pretreatment.