Stabilizing nanoprecipitates in Al-Cu alloys for creep resistance at 300°C

Commercial precipitation-hardened Al-Cu alloys are normally used at temperatures below its ageing temperature of approximate to 225 degrees C, to avoid thermally induced precipitate coarsening and resultant softening. Making such popular Al alloys creep resistant at or above 300 degrees C is thus challenging. Here we present a modified precipitation protocol, exploiting Sc-microalloying and a carefully designed three-step heat treatment to enhance Sc segregation at the matrix/-Al2Cu precipitate interfaces. The stabilized nanoprecipitates enable an order-of-magnitude reduction in creep rate at 300 degrees C, demonstrating the room for microstructure improvement and the potential for property elevation in traditional engineering alloys through innovative processing coupled with synergetic alloying elements. [GRAPHICS] IMPACT STATEMENTA carefully designed precipitation protocol produces stable nanoprecipitates in Sc-microalloyed Al-Cu alloys, rendering an order-of-magnitude elevation of creep resistance at 300 degrees C.