Purification of Ti-Al alloy by cold-crucible induction melting in ultrahigh vacuum

In order to investigate the effect of ultrahigh vacuum melting on the purification of Ti-Al alloy, a 1 kg ultrahigh-purity Ti-45 mol% Al alloy ingot of more than 99.9940 mass% purity after analysis of 40 elements was prepared by cold-crucible induction melting (CCIM) in argon and in ultrahigh vacuum. High-purity aluminium of 99.9986 mass% purity and high-purity titanium of 99.985 mass% purity were used as starting materials. The impurity analysis was done using quadrupole residualgas analysis, chemical analysis, and glow-discharge mass spectrometry (GDMS) analysis. The concentration of gaseous impurities in the ingot was 51 mass ppm (O = 35, N = 11, C = 5, S < 0.5). As a result of GDMS analysis of 36 metallic elements in the ingot, the total amount of metallic impurities was below 8.7 mass ppm, exclusive of 23 elements below their detection limits. The cold-crucible induction melting in UHV is effective in preparing an ultrahigh-purity Ti-Al alloy ingot containing low concentrations of gaseous and metallic impurities.