Ultrafine-grained(UFG)materials exhibit high strengths due to grain boundary strengthening,but grains can grow rapidly if post heat treatment is required,making it challenging to achieve grain boundary and precipitati...Ultrafine-grained(UFG)materials exhibit high strengths due to grain boundary strengthening,but grains can grow rapidly if post heat treatment is required,making it challenging to achieve grain boundary and precipitation strengthening simultaneously.Grain growth stagnation at 525℃(0.87 T_(m),melting point)was observed in a Mg-4Y-3RE alloy fabricated by additive friction stir deposition(AFSD),a novel solidstate additive manufacturing technology.The AFSD processing produced a UFG microstructure and two major second phases,Mg_(41)RE_(5)and nanoparticles containing Y and O.After solid solution treatment(SST)at 525℃for 72 h,no noticeable grain growth occurred.While Mg_(41)RE_(5)particles dissolved into the matrix within 4 h of SST,the nanoparticles remained stable and unaltered.The observed grain growth stagnation is attributed to Zener pinning by these thermally stable nanoparticles.These new findings offer a novel approach to designing UFG materials with exceptional thermal stability for high-temperature applications.展开更多
基金supported by the UKRI Future Leaders Fellowship,[MR/T019123/2]。
文摘Ultrafine-grained(UFG)materials exhibit high strengths due to grain boundary strengthening,but grains can grow rapidly if post heat treatment is required,making it challenging to achieve grain boundary and precipitation strengthening simultaneously.Grain growth stagnation at 525℃(0.87 T_(m),melting point)was observed in a Mg-4Y-3RE alloy fabricated by additive friction stir deposition(AFSD),a novel solidstate additive manufacturing technology.The AFSD processing produced a UFG microstructure and two major second phases,Mg_(41)RE_(5)and nanoparticles containing Y and O.After solid solution treatment(SST)at 525℃for 72 h,no noticeable grain growth occurred.While Mg_(41)RE_(5)particles dissolved into the matrix within 4 h of SST,the nanoparticles remained stable and unaltered.The observed grain growth stagnation is attributed to Zener pinning by these thermally stable nanoparticles.These new findings offer a novel approach to designing UFG materials with exceptional thermal stability for high-temperature applications.
