{"title":"Pseudo Sub-grain Formation and Evolution in a Ti3Al-Nb Based Alloy Induced by B2-BCC Disordering","authors":"Liangliang Liu, Dong Liu, Yuyou Cui, Rui Yang","doi":"10.1007/s11661-024-07530-5","DOIUrl":null,"url":null,"abstract":"<p>The high temperature <i>β</i>/B2 phase field of Ti<sub>3</sub>Al-Nb based alloys was rarely studied due to limitation in experimental technique, but different states of this phase field lead to difference in subsequent phase transformation path and resulting microstructure. By controlling the heating temperature and dwell time of <i>α</i><sub>2</sub>′ → <i>β</i>/B2 transformation and subsequent cooling rate, we achieved a new microstructure consisting of domains of the B2 phase with <i>α</i><sub>2</sub>′ martensite occupying the disordered BCC domain walls, effectively forming a pseudo sub-grain microstructure. It is shown that the domain walls evolved from the disordered <i>β</i> phase in the <i>β</i>/B2 phase field. Such pseudo sub-grain boundaries refine the prior <i>β</i> grains by subdividing them into smaller <i>α</i><sub>2</sub> colonies that form during subsequent heat treatment in the <i>α</i><sub>2</sub>′ + <i>β</i>/B2 phase field upon reheating, and improve the mechanical properties of the alloy.</p>","PeriodicalId":18504,"journal":{"name":"Metallurgical and Materials Transactions A","volume":"220 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Metallurgical and Materials Transactions A","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1007/s11661-024-07530-5","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
The high temperature β/B2 phase field of Ti3Al-Nb based alloys was rarely studied due to limitation in experimental technique, but different states of this phase field lead to difference in subsequent phase transformation path and resulting microstructure. By controlling the heating temperature and dwell time of α2′ → β/B2 transformation and subsequent cooling rate, we achieved a new microstructure consisting of domains of the B2 phase with α2′ martensite occupying the disordered BCC domain walls, effectively forming a pseudo sub-grain microstructure. It is shown that the domain walls evolved from the disordered β phase in the β/B2 phase field. Such pseudo sub-grain boundaries refine the prior β grains by subdividing them into smaller α2 colonies that form during subsequent heat treatment in the α2′ + β/B2 phase field upon reheating, and improve the mechanical properties of the alloy.