Quantifying heterogeneous deformation in grain boundary regions on shock loaded tantalum using spherical and sharp tip nanoindentation

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:737

Article

Weaver, Jordan S.^1,4  Jones, David R.²  Li, Nan¹  Mara, Nathan^1,3  Fensin, Saryu²  Gray, George T., III² 

[1] Los Alamos Natl Lab, Mat Phys & Applicat Div, Ctr Integrated Nanotechnol, POB 1663, Los Alamos, NM 87545 USA

[2] Los Alamos Natl Lab, MST Mat Sci Radiat & Dynam Extreme 8, POB 1663, Los Alamos, NM 87545 USA

[3] Univ Minnesota Twin Cities, Dept Chem Engn & Mat Sci, 421 Washington Ave SE, Minneapolis, MN 55455 USA

[4] NIST, 100 Bur Dr, Gaithersburg, MD 20899 USA

关键词: Spall;    Hardness;    Dynamic deformation;    Grains and interfaces;    Stress/strain measurements;    Electron microscopy;   

DOI  :  10.1016/j.msea.2018.09.075

来源: Elsevier

【 摘 要 】

Grain boundaries play an important role in the overall mechanical performance of metals and alloys; however, isolating the effects of individual grain boundaries remains rather challenging experimentally. In this work, wire-feed, electron beam additively manufactured tantalum is studied under shock loading conditions generating incipient spall damage. Three grain boundaries aligned parallel to the shock direction were isolated inside a single sample. Postmortem metallography showed voids preferentially appeared on two of the three grain boundaries which had high misorientation angles > 30 degrees compared to the third grain boundary with a relatively lower misorientation angle < 10 degrees. Nanoindentation in grain boundary regions for both pyramidal and spherical tips showed characteristically different strain hardening trends for each grain boundary. Significant local strain hardening is present on both sides of one high angle grain boundary, while strain softening is captured at the other high angle grain boundary. A negligible trend of either hardening or softening is shown in the vicinity of the single low angle grain boundary. This leads to the conclusion that the trend of strain hardening/softening in grain boundary regions is not monotonically correlated to the susceptibility of specific grain boundaries to an increased propensity for void damage.

【 授权许可】

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