Quasi-static compression of shock loaded, single crystal tantalum micropillars

This paper presents the mechanical behaviour of single crystal Ta (6.5 GPa-22 GPa) 1-D shocked along the three principal crystallographic directions [100], [110] and [111]. Room temperature mechanical testing was carried out on micropillars to make possible precise load and displacement measurements. The findings exhibit a marked variation in the flow curve and strain hardening between the three orientations, and relative changes are noticed with shock loading. The yield strength (YS) increases linearly as a function of shock load. The YS was highest along [111] (282 MPa) compared with the [100] and [110] orientations (194 and 206 MPa). The strain hardening rates without pre-shock loading are found to be in the order [111] > [100] > [110] and this is not altered by pre-shock loading. Deformation was accomplished by slip on {112} planes. Further, assessments are considered to identify effective plastic strain accumulation during shock loading. The accumulation of effective plastic strain was found to be similar for all directions for shock loading up to 6.5 GPa, however, above 15 GPa the effective strain was lower for [110] compared to [100] and [111] directions. An attempt is made here to assess the flow curve hardening behaviour and variation in yield strength based on a different combination of pair orientation to throw some light into materials response at high-pressure shock loading.

Automated summary

This study investigates the mechanical behavior of single crystal Ta shocked along three principal crystallographic directions. It is found that the flow curve and strain hardening vary significantly between the orientations, and shock loading causes relative changes. Yield strength increases linearly with shock load, with the [111] orientation having the highest yield strength. Deformation occurs through slip on {112} planes, and the accumulation of effective plastic strain varies with shock loading above 15 GPa.