Designing hetero-structured ultra-strong and ductile Zr-2.5Nb alloys:Utilizing the grain size-dependent martensite transformation during quenching

作     者：S.Y.Liu J.Y.Zhang J.Kuang X.Y.Bao D.D.Zhang C.L.Zhang J.K.Yang G.Liu J.Sun S.Y.Liu;J.Y.Zhang;J.Kuang;X.Y.Bao;D.D.Zhang;C.L.Zhang;J.K.Yan;G.Liu;J.Sun

作者机构：State Key Laboratory for Mechanical Behavior of MaterialsXi’an Jiaotong UniversityXi’an 710049China 

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

年 卷 期：2022年第125卷第30期

页      面：198-211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：financially supported by the National Natural Science Foundation of China(Nos.92163201,U2067219,51722104,51790482,51801147,and 51761135031) the National Key Research and Development Program of China(No.2017YFA0700701) the 111Project 2.0 of China(No.BP2018008) the Fundamental Research Funds for the Central Universities(Nos.xtr022019004 and xzy022021014) 

主　　题：Zr-Nb alloys Heterogeneous structure Martensitic transformation Grain size Strength 

摘      要：To further improve the service performance of Zr-2.5Nb alloy worked as pressure tubes in pressurized heavy water reactors,more investigation about the microstructure and thermomechanical processing route of Zr-2.5Nb alloy need to be *** this work,a hetero-structured Zr-2.5Nb alloy was prepared by applying a novel *** analysis reveals that the alloy exhibits a grain sizedependent martensite substructure transition during post-rolling *** hetero-structure consists of equiaxed primaryαgrains and the lamellae groups containing both parallelα’dislocation martensite andα’twin *** with the previously reported Zr-Nb alloys,the present Zr-2.5Nb alloys manifest the highest yield strength(∼710 MPa),together with a high ultimate tensile strength(∼844 MPa)and good ductility(∼17.1%).The enhanced mechanical properties are found to arise from the properly controlled fraction/size of the two types of martensite,which not only significantly strengthens the alloy but also contributes to a stronger strain hardening.A model based on the grain-size-dependent critical resolved shear stress for dislocation slip and twinning has been proposed to explain theα’martensite substructures transition at a critical grain size dc=3.3μ*** this size,the critical resolved shear stress(CRSS)for twinning is higher than that for the***,theα’dislocation martensite is more favorable to ***,theα’twin martensite would exhibit a high *** present work indicates that making use of the grain size-dependent martensite transformation to tailor the heterostructure in Zr alloys is an effective strategy to overcome the strength–ductility trade-off in the material.