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

Journal Article · · Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing

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° compared to the third grain boundary with a relatively lower misorientation angle < 10°. 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. As a result, 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.

Research Organization:
Los Alamos National Laboratory (LANL)
Sponsoring Organization:
LDRD; USDOE
Grant/Contract Number:
AC52-06NA25396
OSTI ID:
1477707
Alternate ID(s):
OSTI ID: 1636607; OSTI ID: 22796686
Report Number(s):
LA-UR-18-29241; {"Journal ID: ISSN 0921-5093",""}
Journal Information:
Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing, Journal Name: Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing Journal Issue: C Vol. 737; ISSN 0921-5093
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

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