Research on Transient Behavior of Aluminium in Laser Micro-Molton Pool

To explore reaction mechanisms and proper effects of aluminium in laser micro-molton pool, experiments of laser cladding (Ti+1-8%Al) on Ti-6Al-4V by pulsed Nd:YAG had been carried out. The microstructures, microhardness and phases of the cladding layers with different weight percentage of Al were investigated. The content of Al was quantitatively determinated when ordering α2 ceramic phase (Ti3Al matrix) were formed. And the friction and wear properties of the cladding layers were examined in atmosphere. It was found that the microstructure of the cladding layers included cellular crystals, columnar crystals, arborescent crystals and dispersive white granules. The α2 ceramic phase was formed when the content of Al was 6%wt. With the increasing of weight percentage of Al, the number and size of arborescent crystals increased obviously, as well as the microhardness, the maximum was 957.9Hv, 1.3-1.5 times of the layers with below 6%wt Al. Inversely, the wear resistance of the laser cladding layers was improved gradually. Friction coefficient, wear extent and wear rate decreased. 0.55-0.7 times of the layers with below 6%wt Al.