Research on laser rapid directional solidification with ultra-high temperature gradient

Detailed laser surface remelting experiments of three kinds of Cu-Mn alloys were carried out to study the effects of technological parameters (scanning velocity, laser output power) on the growth direction of microstructure in the molten pool. The experimental results show that growth direction of microstructure is strongly affected by laser technological parameters and alloy composition. Ultra-high temperature gradient directional solidification can be realized on the surface of samples by laser surface remelting, whose temperature gradient can reach 10⁶ K/m and growth velocity can reach 24 mm/s, and the solidification microstructure grows along the laser beam scanning direction. In order to obtain ultra-high temperature gradient and rapid directional solidification with laser surface remelting, the key problems are: 1) to ensure temperature gradient in the molten pool parallel to laser beam scanning direction; 2) to select adequate technological parameters to ensure cellular growth.