Structure formed by laser heat treatment in heat-resistant nickel alloys and its stability in subsequent aging

1. Laser heat treatment (both with and without fusion of the surface) of KhN59KVMTYu and KhN63KVMTYu heat-resistant aging alloys may change the dispersion of the structure in surface layers up to 1 mm thick and more. 2. In laser heat treatment with fusion of the surface of KhN59KVMTYu alloy eutectic colonies of γ+γ′-phases up to 0.2–0.3 μm in size are formed together with areas of finely dispersed γ′-phase (size 20–40 nm) uniformly distributed in the matrix. To prevent appearance of them it is desirable to conduct laser heat treatment without fusion of the surface. 3. The thermal stability of the surface layers formed in laser heat treatment is higher than after stepped aging. The maximum size of the γ′-phase particles is less and the size distribution of the particles is more uniform.