Abstract:The activity coefficients of components in Nb3Al melt were calculated. On the basis of the activity coefficients, the evaporation behaviors, including the evaporation dynamic and the evaporation loss of Al in the Nb3Al melt during the induction skull melting (ISM) process were studied systematically. The results show that the evaporation-controlling mode of Al in the alloy melt is a double controlling mode, i.e. the diffusion of evaporation element in melt boundary layer and the evaporation reaction, under the conditions thatp=1.333 Pa and the scope of melt temperature is 2 235~2 635 K. When the melt temperature is 2385K(the superheat is 100K), the evaporation-controlling mode varies from the double controlling mode to a single controlling mode (the evaporation reaction on the surface of melt) if the vacuum chamber pressure is above 133 Pa.

Key words: Nb3Al alloy; induction skull melting; Al evaporation