Phase Evolution and Redistribution of Intermetallic Precipitates during Thermo-Mechanical Processing of a Zn-۱Mg-۱Cu-۰.۲Sr

This work explores the structural evolution and strengthening response of the biodegradable Zn-۱Mg-۱ Cu-۰.۲Sr alloy subjected to sequential homogenization and hot rolling. The alloy was homogenized at ۳۰۰ °C for ۱۰h and subsequently hot-rolled at ۲۵۰ °C with ۲۰% thickness reduction to evaluate phase redistribution and mechanical enhancement. Rietveld-based quantitative analysis showed that the fraction of the brittle MgZn phase fell sharply from ۱۷.۹ wt.% to ۹.۴ wt.%, and MgZn۲ and CuZns rose from ۱۴.۶ wt.% to ۱۹.۸ wt.% and from ۱۰.۳ wt.% to ۱۷.۷ wt.%, respectively. Optical microscopy confirmed substantial refinement of the intermetallic grains and fragmentation of SrZn۱۳ particles into sub-micrometric dispersions oriented along the rolling direction. These structural modifications translated to a clear improvement in hardness, increasing from ۸۰.۴۵ HV in the homogenized state to ۱۰۶.۹۳ HV after rolling, indicating roughly a ۳۳% hardness gain. The enhancement primarily stems from dislocation accumulation and dispersion strengthening caused by the fractured secondary phases. Overall, the combined thermo-mechanical processing developed a finer, more stable, and textured microstructure.

کلیدواژه ها:

Hot Rolling ، Zn-bassed alloy ، Biocompatibility ، Phase transformation