Jean-Francois Stohr

Comparison of the quench rates attained in gas-atomized powders and melt-spun ribbons of Co- and Ni-base superalloys: influence on resulting microstructures

The cooling rates of gas-atomized Stellite 6 powders range from 103 to 106 K sec−1 for 400 to 10μm diameter powder particles, respectively. The microstructures vary from the equiaxed type in the coarser particles to dendritic and finally microcrystalline in the finer particles. In the melt-spun ribbons, the microstructure along a cross-section of the ribbon changes from microcrystalline at cooling rates higher than 107 K sec−1 to columnar dendritic at cooling rates of the order of 106 K sec−1.