Study On The Dissolving Process Of High Melting Point Component In TiAl Melt During ISM Process

The dissolving processes of high melting point component in alloy melt under different conditions were studied through theoretical analysis and experiment.In thermodynamics, the value of chemical potential is used to judge the dissolving tendency of high melting point component.In kinetic, the dissolving of high melting point component can be divided to three stages that are molten, diffusion and uniformity. The degree of dissolving is concerning with the degree of chemical potential. The diffusion process was divided into two conditions, with stirring and without stirring. The two conditions were studied respectively.Under the condition without stirring, the half-infinity diffusion theoretical model of high melting component Fe dissolving in Al melt was developed. The solute distribution curves of high melting component Fe with different time and positions were obtained. Under the condition with stirring, dissolving quantity of pure Nb in Ti-Al alloy is related with melting time and temperature. Diffusion layer thickness and mass transport coefficient were calculated by Machlin model, and the relationship of dissolving quantity and time is obtained.The dissolving of Fe in Al melt with a resistance furnace was carried out to investigate the diffusion process. Dissolving quantity and melt diffusion layer thickness of melt containing 17.35wt%Fe were achieved. The experimental result is consistent to the theoretical model.9 groups dissolving experiments of Nb in Ti-46Al melt with ISM were performed at different melting power of 23kW, 35kW, 40kW, 50kW, 55kW and different period of 7min, 14min, 21min respectively. The dissolving quantity and the diffusion boundary layer thickness under different conditions were obtained. The higher power and longer time are, the less Nb quantity remains. The experimental result is consistent to the theoretical model.Based on the experiment results about ISM process, the influence of the melting power on the diffusion layer thickness was analyzed. The results show that the diffusion layer thickness decrease with the increase of the melting power is mainly because that the flow velocity increased by melting power.