Refining effect of TiAl intermetallic compounds prepared by hydrogen plasma arc melting from scraps of Ti-Al mixture

Abstract

TiAl intermetallic compounds were prepared using scraps of a Ti-40at%Al mixture via hydrogen plasma arc melting (HPAM) and the refining effect was investigated. HPAM was performed under atmospheric pressure condition, which was satisfied by introducing an Ar + 20 vol%H2 gas mixture in a vacuum atmosphere. The mixture scraps and the prepared TiAl intermetallic compounds ingots were analyzed using X-ray diffraction analysis, oxygen/nitrogen analyzer, and glow discharge mass spectrometry. As a result of the study, the separated Ti and Al were dissolved and only γ-TiAl phase was observed. The oxygen concentration of the TiAl intermetallic compounds decreased with the increase in melting time. The plane spacing and lattice parameter decreased owing to the oxygen reduction from the γ-TiAl phase in the refined TiAl intermetallic compounds. The concentration of impurities of the refined TiAl intermetallic compounds for 30 min was 49.35 ppm, which showed a removal degree of 65.52% compared with that of the mixture scraps.