粉末热挤出Al-Mn-Mg-Sc-Zr合金的高温拉伸性能及多尺度析出相演化机制OA

Al-Mn-Mg-Sc-Zr alloys were fabricated by gas atomization,cold isostatic pressing,and hot extrusion,and their high-temperature tensile properties and multiscale precipitate evolution from room temperature to 300℃ were investigated.The as-extruded alloy has a fine equiaxed grain structure with micron-sized Al6Mn particles and nanoscale Al3(Sc,Zr)precipitates dispersed in the matrix,whereas discontinuously distributed MgO particles are present along the grain boundaries.At room temperature,the strength of the alloy is high,with an ultimate tensile strength of 460.3 MPa and a yield strength of 422.8 MPa,but the elongation is limited to 3.9％.At 200℃,a favourable strength-ductility balance is obtained,with an ultimate tensile strength of 219.8 MPa,a yield strength of 200.2 MPa,and an elongation of 23.8％.Microstructural analysis indicates that the Al6Mn phase coarsens significantly at elevated temperatures,leading to a weakened strengthening effect.In contrast,the nanoscale Al3(Sc,Zr)precipitates with an ordered L12 structure maintain coherent interfaces with the α-Al matrix and exhibit excellent thermal stability because of the sluggish diffusion of Sc and Zr,thereby continuously contributing to strengthening.Moreover,a small amount of discontinuously distributed MgO particles is present at the grain boundaries.The elevated-temperature tensile behavior of the alloy is governed primarily by the distinct thermal stability of multiscale precipitates.