Deformation mechanism of bimodal microstructure in Ti-6Al-4V alloy:The effects of intercritical annealing temperature and constituent hardness

作     者：Yan Chong Tilak Bhattacharjee Yanzhong Tian Akinobu Shibata Nobuhiro Tsuji Yan Chong;Tilak Bhattacharjee;Yanzhong Tian;Akinobu Shibata;Nobuhiro Tsuji

作者机构：Department of Materials Science and EngineeringKyoto UniversityKyotoJapan Department of Materials Science and EngineeringUniversity of CaliforniaBerkeleyCAUSA Elements Strategy Initiative for Structural Materials(ESISM)Kyoto UniversityKyotoJapan Key Laboratory for Anisotropy and Texture of MaterialsSchool of Materials Science and EngineeringNortheastern UniversityShenyang 110819China Research Center for Metallic WiresNortheastern UniversityShenyang 110819China 

出 版 物：《Journal of Materials Science & Technology》 (材料科学技术（英文版）)

年 卷 期：2021年第71卷第12期

页      面：138-151页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：financial support from Cross-ministerial Strategic Innovation Promotion Program(SIP)supported by the Cabinet Office of Japanese government and the Elements Strategy Initiative for Structural Materials(ESISM)in Kyoto University supported by the Ministry of Education,Culture,Sports,Science and Technology(MEXT),Japan support by the Fundamental Research Funds for the Central Universities under grant No.N180204015 

主　　题：Ti-6Al-4V Bimodal microstructure Intercritical annealing temperature Strain distribution dislocation 

摘      要：The so-called bimodal microstructure of Ti-6 Al-4 V alloy,composed of primaryαgrains(α_(p))and transformed β areas(β_(trans)),can be regarded as adual-phasestructure to some extent,the mechanical properties of which are closely related to the sizes,volume fractions,distributions as well as nanohardness of the two *** this study,the volume fractions of primaryαgrains(vol.%(α_(p)))were systematically modified in three series of bimodal microstructures with fixed primaryαgrain sizes(0.8μm,2.4μm and 5.0μm),by changing the intercritical annealing temperature(T_(int)).By evaluating the tensile properties at room temperature,it was found that with increasing T_(int)(decreasing vol.%(α_(p))),the yield strength of bimodal microstructures monotonically increased,while the uniform elongation firstly increased with T_(int)until 910°C and then drastically decreased afterwards,thereby dividing the T_(int)into two regions,namely region I(830-910°C)and region II(910-970℃).The detailed deformation behaviors within the two regions were studied and compared,from the perspectives of strain distribution analysis,slip system analysis as well as dislocation *** bimodal microstructures in region I,due to the much lower nano-hardness ofβ_(trans)thanα_(p),there was a clear strain partitioning between the two constituents as well as a strain gradient from theα_(p)/β_(trans)interface to the grain interior ofα_(p).This activated a large number of geometrically necessary dislocations(GNDs)near the interface,mostly with components,which contributed greatly to the extraordinary work-hardening abilities of bimodal microstructures in region *** increasing T_(int),theα_(p)/β_(trans)interface length density gradually increased and so was the density of GNDs with components,which explained the continuous increase of uniform elongation with T_(int)in this *** bimodal microstructures in region II,where the nano-hardness ofβ_(trans)andα_(p)were comparable,neither a clear s