Twinning stress τtw is an important constitutive parameter of crystal solids. Routinely, measured (by quasi-static tension/compression tests) values of τtw are characterized by strong scatter while the temperature domain of such measurements is seriously limited due to the great difference between the τtw and τcrssat ambient and high temperatures. The presently suggested approach to measure τtw consists of two steps. The first step is determination of concentration Ntw(h) of shock-generated twins as a function of the propagation distance h. This is done based on metallographic examinations of shock-loaded and softly recovered 3 - 6 mm thick sample of the studied material. The second step is calibration of the shear stress τ(h), responsible for the twins' generation, by series of VISAR-instrumented impact tests (of the same strength) with the samples of different thickness h. The shear stressτ(h*), corresponding to the Ntw(h*) = 0 is the material's twinning stress τtw. Using this approach, the twinning stress of commercially pure vanadium was determined over 300 - 700 K temperature range and so-measured ttw values were found to be in a good agreement with ttw values measured in vanadium at low (20 K) temperature. Israel Science Foundation (Grant 441/18).
|Title of host publication||APS March Meeting 2021|
|State||Published - 2021|