Ultrasonic Strengthening of the Mechanical Properties of AZ31B Magnesium Alloy via Ti/SiC Powder Infiltration and Microstructural Refinement

This study investigated the mechanical properties of AZ31B magnesium alloy using the ultrasonic strengthening grinding process (USGP) with a mixed medium of ZrO 2 balls, Ti, and SiC powders. Different USGP treatment durations were performed. Results show that suitable USGP treatment leads to significant enhancement in both ultimate tensile strength (UTS) and total elongation (TE). Key findings reveal that the sample subjected to 4 min of USGP exhibits superior tensile strength, with an increase of 25.61% compared to the untreated sample at a tensile rate of 1 mm/min. For the sample subjected to 10 min of USGP, tensile strength is slightly reduced yet remains 21.4% higher than that of the untreated sample, while ductility reaches its maximum value, showing a remarkable improvement of 54.54% compared to the untreated sample. The phenomenon can be attributed to a synergistic interplay between powder embedding and plastic deformation. Severe plastic deformation induced by shot peening leads to significant grain refinement and an increase in dislocation density. Concurrently, embedded ductile Ti particles with a hexagonal close‐packed structure enhance fracture strain of the composite through coordinated deformation with the matrix, while hard SiC particles contribute to strengthening via load‐transfer effects and Orowan bypass mechanisms.