In situ study of phase transformations in Ti-6Al-4V-xH alloys
(1. National Key Laboratory for Precision Hot Processing of Metals, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China;
2. State Key Laboratory of Nonferrous Metals and Processes, BeijingGeneral Research Institute for Nonferrous Metals, Beijing 100088, China)
2. State Key Laboratory of Nonferrous Metals and Processes, BeijingGeneral Research Institute for Nonferrous Metals, Beijing 100088, China)
Abstract: Thehydrogen-induced microstructure evolution and phase transformations in Ti-6Al-4V alloy during heating and cooling were studied. The specimens were heated to 1273K and subsequently cooled to room temperature. The hydrogen content is up to 0.8% (mass fraction). The hydrogen-induced dynamic phase transformations and the corresponding mechanisms were analyzed. When the hydrogen content increases, the β transus temperature significantly decreases and the magnitude decreases, and the volume fraction of β phase increases. During heating, the phase transformations in hydrogenated Ti-6Al-4V alloys can be divided into three stages, and the phase transformation order is δ→α+H2↑？δ+α′→βH？α′→αH+βH？αH→α+H2↑？α→β？βH→β+H2↑. In addition, the relationship among hydrogenation and Ms and Mf of α′ martensite were determined.
Key words: titanium alloy; phase transformation; hydrogen; in situ