Spall Failure of ECAE Mg-Al Alloys at Extreme Strain Rates: Influence of a Refined Precipitate and Grain Microstructure

Christopher S. DiMarco; Peter Lim; Debjoy Mallick; Laszlo Kecskes; Timothy P. Weihs; K. T. Ramesh

doi:10.3390/met13030454

Metals (Feb 2023)

Spall Failure of ECAE Mg-Al Alloys at Extreme Strain Rates: Influence of a Refined Precipitate and Grain Microstructure

Christopher S. DiMarco,
Peter Lim,
Debjoy Mallick,
Laszlo Kecskes,
Timothy P. Weihs,
K. T. Ramesh

Affiliations

Christopher S. DiMarco: Hopkins Extreme Materials Institute, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
Peter Lim: Hopkins Extreme Materials Institute, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
Debjoy Mallick: Hopkins Extreme Materials Institute, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
Laszlo Kecskes: Hopkins Extreme Materials Institute, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
Timothy P. Weihs: Hopkins Extreme Materials Institute, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
K. T. Ramesh: Hopkins Extreme Materials Institute, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA

DOI: https://doi.org/10.3390/met13030454
Journal volume & issue: Vol. 13, no. 3
p. 454

Abstract

Read online

The development of advanced materials for extreme dynamic environments requires an understanding of the links between the microstructure and the response of the material (i.e., Materials-by-Design). Spall failure significantly limits material performance at high strain rates, but our understanding of the influence of microstructure on spall strength is limited. While models suggest that increasing the static yield strength by adding precipitates or refining grain size can improve the spall strength, it is possible that the associated increase in nucleation sites may have deleterious effects on spall performance. Herein, we examine spall failure of a Magnesium-Aluminum system with precipitation and grain size strengthening through novel high-throughput laser-driven micro-flyer (LDMF) impact experiments. Six microstructures are investigated, four with grain sizes around 2–3 μm and precipitates around 0.5–1 μm, and two that are precipitate-free with grain sizes around 500 μm at six and nine percent Aluminum contents. The LDMF method allows us to detect differences in spall strength with relatively small changes in microstructure. The spall strength is observed to be strongly affected by varying levels of precipitates and consistently shows a notable reduction in average spall strength around 8–19% with the addition of precipitates, with values ranging from 1.22–1.50 GPa. The spall strength is also seen to decrease with the refinement of grain size independent of composition. However, this decrease is small compared to the hundred-fold grain size reduction. While ductile void growth is observed across all samples, greater variability and a further decrease in strength are seen with an increasing numbers of non-uniformly dispersed precipitates.

Published in Metals

ISSN: 2075-4701 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Technology: Mining engineering. Metallurgy
Website: http://www.mdpi.com/journal/metals

About the journal

Abstract

Keywords