Failure mode and dynamic behavior of nanophase iron under compression

Journal Article · Fri Dec 17 04:00:00 EST 1999 · Scripta Materialia

DOI:https://doi.org/10.1016/S1359-6462(99)00312-7· OSTI ID:20023112

Jia, D; Ramesh, K T; Ma, E

Materials with ultra-fine grains down to the nanophase range (<100 nm) have been attracting considerable interest because of their unique properties compared with conventional materials. In general, the understanding of the deformation behavior of ultrafine- and nano-grained metals and alloys is still in the rudimentary stage. In this paper, the authors report on the compressive deformation behavior and failure mode of near full-density (99.2% of theoretical density) elemental Fe with an average grain size of 80 nm. Even less is known about the behavior of ultrafine- or nano-grained alloys under dynamic loading of high strain rates. Such response is relevant to possible applications of these alloys under impact conditions, such as for kinetic energy penetrators currently under investigation. The authors will present the results of high-strain-rate (Kolsky bar) tests for nano-Fe and compare them with those obtained in quasi-static compression tests of the same material. The authors demonstrate that little strain rate sensitivity is observable in the rate of 10{sup {minus}4} to 3 x 10{sup +3} s{sup {minus}1}, in sharp contrast to the strong rate sensitivity known for conventional coarse-grained bcc Fe. The weak rate dependence is correlated with shear banding as the dominant deformation and failure mechanism. This strain rate hardening behavior, together with the high strength, absence of strain hardening, and failure mechanism observed, are discussed in the context of potential applications for penetrator materials.

• Research Organization: Johns Hopkins Univ., Baltimore, MD (US)
• OSTI ID: 20023112
• Journal Information: Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 1 Vol. 42; ISSN 1359-6462; ISSN SCMAF7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMPRESSION STRENGTH
DEFORMATION
FAILURES
GRAIN SIZE
IRON
POWDERS
SAMPLE PREPARATION
STRAIN RATE