Vacuum Magnetic Levitation Refining for Titanium Aluminum Alloy Prepared by Electro-thermal Reduction

The theory and experiment results for vacuum magnetic levitation refining of titanium aluminum alloy（TiAl alloy） indicate that increasing the vacuum degree and heating current can help to decrease the oxygen content in the alloy,while it suffers from Al volatilization with a drastic process which is adverse to composition control and inclusion removal for the alloy.At heating current of 60 A,vacuum degree of 400 Pa with Ar and refining time of 30 min,the slag inclusions of coarse particle can be effectively removed.After two times of refining at the same conditions,the oxygen and nitrogen content of the alloy can be decreased to 0.50% and 0.55%,respectively.The microstructure of TiAl alloy after two times of refining is near layer tissue composed of γ and α₂ structures,with TiAl,Ti₂AlN and Ti₂Al as the main phases.Brittle fracture at room temperature can be attributed to the obtained alloy,with bending strength of 258 MPa and vickers hardness of 486.