Mechanisms of plastic deformation and mechanical strengthening in nano-scale Ti-Ti_(2)Cu eutectoids:A study combined molecular dynamics simulation and experiment  

作　　者：Haodong Wang Chun Yu Moqiu Li Yi Zheng Junmei Chen Jieshi Chen Hao Lu Jijin Xu 

机构地区：[1]Shanghai Key Laboratory of Materials Laser Processing and Modification,School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China [2]School of Materials Science and Engineering,Shanghai University of Engineering Science,Shanghai 201602,China

出　　处：《Journal of Materials Science & Technology》2024年第26期146-159,共14页材料科学技术(英文版)

基　　金：supports by the National Nature Science Foundation of China(No.52275354);the Na-tional Key R&D Program of China(No.2018YFA0702900).

摘　　要：Ti-Cu eutectoid or near-eutectoid alloys were found to possess exceptional high strength owning to the nano-scale lamellar structure of Ti_(2)Cu andα-Ti after additive manufacturing,they are potential candidates for high-performance materials.To reveal the deformation and strengthening mechanisms,the molecular dynamics(MD)simulations and experimental analysis were carried out upon Ti-Ti_(2)Cu lamellae.In this work,we focused on revealing the interface dislocations(IDs)pattern and its effects on the dynamic evolution of the lattice dislocations(LDs)at the Ti/Ti_(2)Cu interface with(0001)α//(013)Ti_(2)Cu orientation relationship.Atomistic simulations depicted that the equilibrium Ti/Ti_(2)Cu interface contains three groups of partial dislocations which dictate two interfacial coherent structures with low stacking fault energy.Each ID consists of several segments,connected by atomic steps with identical direction.The nucleation sites of LDs under external loading locate at the intersection between the dislocation segment and the atomic step,which is related to the local high atom strain.Under compression deformation,the100{011}and331{103}slip systems in Ti_(2)Cu,and the112¯3{101¯1}slip system inα-Ti are activated,achieving a co-deformation mechanism in the Ti-Ti_(2)Cu multilayers.The dislocation-interface interactions are responsible for the deformation plasticity and in turn governs the mechanical strengthening.During nanoindentation tests,larger hardness(∼6.2 GPa)and smaller activation volume(∼12b3)were found in the Ti-Ti_(2)Cu lamellae,which is mainly ascribed to the presence of high-density lamellae interface and confined layer slip,resulting in interface-mediated dislocation annihilation/deposition and consequent high strain hardening.The MD simulations,nanoindentation tests and TEM investigations of interlayer dislocation activity support the strengthening mechanism of dislocation-interface interactions.

关 键 词：Ti-Ti_(2)Cu eutectoids Interface DISLOCATION Molecular dynamics 

分 类 号：TG1[金属学及工艺—金属学]