Phase Transformations of the Ti- 5Al-1Sn -1Cr - 1Fe Alloy

• Main Author: 簡正源
• Other Authors: Chao, Chih-Yeh
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/78711472949433228887

碩士 === 國立屏東科技大學 === 機械工程系所 === 97 === During the continuous hot-rolling, the ultimate tensile strength, yielding strength and elongation of the Ti-5Al-1Sn-1Cr-1Fe alloy are in the range of 980~1060MPa, 860~1000MPa and 24-40%, respectively. The main purposes of the present studies are to investigate the effects of heat treatment on the microstructures of the alloy. Some results are described as following. Being heated on 1030℃ for 1 hour, the microstructure of the present alloy is lamellar twin martensite. When heated on 900℃ for 1 hour, the micro- structure of the present alloy is a mixture (α+β) duplex phases. In addition, a martensite transformation would occur within the β-phases region resulting in forming a martensite with high density dislocation during the quenching. Being heated at 800℃, the microstructure of the alloy is a mixture (α+β) phase. In the meanwhile, some precipitates with an hcp superlattice structure were found within the α-phase region. During the aging processing, 480-540℃ for 1-8 hours, some ω-phase precipitates formed within the matrix. Moreover, base on the examination of scanning electron micrograph, the α/β transition temperature of the present alloy will be in the range between 965℃ and 980℃, and the temperature of the martensite transition (Ms) being in the range between 815℃ and 830℃.