Small-scale analysis of brittle-to-ductile transition behavior in pure tungsten  

作　　者：Yeonju Oh Won-Seok Ko Nojun Kwak Jae-il Jang Takahito Ohmura Heung Nam Han 

机构地区：[1]Department of Materials Science and Engineering&Research Institute of Advanced Materials,Seoul National University,Seoul 08826,South Korea [2]School of Materials Science and Engineering,University of Ulsan,Ulsan 44610,South Korea [3]Division of Materials Science and Engineering,Hanyang University,Seoul,04763,South Korea [4]National Institute for Materials Science,1-2-1 Sengen,Tsukuba,Ibaraki 305-0047,Japan

出　　处：《Journal of Materials Science & Technology》2022年第10期242-258,共17页材料科学技术（英文版）

基　　金：supported by the National Research Foundation of Korea(NRF)grant funded by the Ministry of Science,ICT(MSIT)[NRF-2020R1A5A6017701,NRF-2019M3D1A1079214,and NRF-2020R1A6A3A13076748];the ITER Technology R&D Programme。

摘　　要：Tungsten as a material exhibits broad and increasingly important applications;however,the characterization of its ductile-to-brittle transition(BDT)is currently limited to large-scale scenarios and destructive testing.In this study,we overcome this challenge by implementing small-scale techniques to provide a comprehensive understanding of the BDT behavior of pure tungsten.In order to predict the failure mode at various temperature ranges,the practical fracture analysis diagram has been proposed to describe the resistance to shear flow and cracking behavior with temperature.High temperature nano-indentation tests have provided the inherent mechanical responses corresponding to the maximum shear stress at various temperatures,which is required for dislocation activities in an atomic scaled activation volume.On one hand,atomistic simulations have provided the temperature dependence of brittle fracture stress,where the atomic bonds break due to intergranular or intragranular fracture.We considered four tungsten specimens having various microstructures prepared using different processing conditions of cold-rolling and post-annealing,and their BDT ranges were inferred using the obtained fracture analysis diagram with the statistical data processing.The fracture analysis diagram of each specimen obtained were compared with the direct observation of fracture responses in macroscopic mechanical tests,which conclusively indicated that the small-scale inherent mechanical properties are greatly relevant to the macroscopic BDT behavior in pure tungsten.Based on the BDT estimations by small-scale characterization,we provided further insights into the factors affecting the BDT behavior of tungsten,focusing on the contributions of different types of dislocations.

关 键 词：Brittle-to-ductile transition Nano-indentation Molecular dynamics DISLOCATION TUNGSTEN 

分 类 号：TG146.411[一般工业技术—材料科学与工程]