Plasticity-induced temperature and texture evolution under dynamic uniaxial compression*

A crystal uniaxially loaded to extreme pressures often relieves the extraordinary shear stresses built up during compression via rapid plastic deformation. Plasticity under extreme loading conditions is a complex process whose character varies dramatically with the details of the applied compression path. Innovations on both experimental and computational fronts have given us glimpses into the lattice-level nature of plasticity under dynamic compression: ultrafast x-ray diffraction platforms allow us to measure directly the changes in crystal structure and orientation (i.e. texture) precipitated by plasticity at pressures approaching the terapascal scale; such measurements can be complemented by both large-scale molecular dynamics simulations and by sophisticated continuum-level plasticity models built from lower-length-scale simulations. In spite of this progress, fundamental questions such as ‘Which plasticity mechanisms will become active under compression?’ and ‘How much heating will they cause?’ remain difficult to answer for all but the most intensively studied materials. In this talk, I review recent progress and outstanding questions regarding the temperature and texture evolution brought about by plasticity under dynamic compression conditions. I discuss two experiments investigating plastic-work heating, the first measuring heating during rapid dynamic release of tantalum by measurement of its thermally-induced strains [1], the second constraining the heating caused by plastic work in diamond ramp-compressed to two terapascals by analysis of its path through phase space [2]. I then present a series of investigations into plasticity-induced texture evolution under shock compression, focusing on a novel multiscale strength model of tantalum that predicts with unprecedented accuracy its texture evolution in nanocrystals loaded to around 100 gigapascals [3].