Vacuum Magnetic Levitation Refining for Titanium Aluminum Alloy Prepared by Electro-thermal Reduction
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摘要: 真空磁悬浮精炼TiAl合金理论及试验研究表明:提高真空度和增大加热电流有利于降低合金中氧含量,但是Al元素挥发严重,精炼过程剧烈,不利于合金成分控制和渣夹杂物去除。加热电流60 A,真空度400 Pa (通入氩气),精炼时间30 min条件下,合金中大颗粒的渣夹杂物得到有效去除,相同工艺条件下,精炼两次后,合金中O含量降低到0.50%,N含量降低到0.55%。精炼两次后得到的TiAl合金的组织为近层片组织,由γ和α2组织构成,主要物相由TiAl、Ti2AlN和Ti2Al相组成,得到了目标TiAl合金的微观组织和相组成。该工艺制备的TiAl合金为室温脆性断裂,弯曲强度为258 MPa,维氏硬度(HV)为486。Abstract: 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.
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