A transmission electron microscopic study of pure tantalum and tantalum-tungsten alloys explosively shocked at a peak pressure of 30GPa was presented. While no omega phase was found in shock-recovered pure Ta and Ta-5W which mainly contain a cellular dislocation structure, a shock-induced omega phase was found in Ta-10W which contained evenly distributed dislocations with a density higher than 1012/cm2. The shock-induced α(bcc) → ω(hexagonal) transition occurred when the dynamic recovery of dislocations becomes largely suppressed in Ta-10W shocked under dynamic-pressure conditions. A dislocation-based mechanism was proposed for the shock-induced phase transformation.

Shock-Induced Phase Transformation in Tantalum. L.L.Hsiung: Journal of Physics - Condensed Matter, 2010, 22[38], 385702