Co-Existence of Multiple Phases in a Dilute Al-Sc-Zr-Y-Co-Ni-Si Alloy

A dilute Al-0.083Sc-0.21Zr-0.07Y-0.025Co-0.063Ni-0.10Si (in wt.%) alloy is investigated by hardness and conductivity tests and phase obervation via TEM, HREM and STEM-EDS analysis. The results showed that the alloy achieved a peak hardness of 54.5 HV after annealing at 400°C for 36h while electrical conductivity also reached a plateau. Al 3 (Sc,Zr,Y) phase, AlFeNi phase and AlScNiSi phase co-exist in the alloy. Al 3 (Sc,Zr,Y) phase possessed spherical shape with a dense distribution and a size range of 6-13nm, the average size, volume fraction and number density were 9.0nm, 0.38% and 6.07×10 21 , respectively. The quantity of AlFeNi phase and AlScNiSi phase are quite small and they had a sparse distribution. Thereinto, the former one possessed rod shape and was coherent with the matrix. Co did not participiate phase formation. This provided a new thought for heat-resistant alloy design.