The Effect of Pressure on the Tensile Properties of Several Metals and Other Materials

Tension tests to fracture under superposed hydrostatic pressure reaching to nearly 30 000 kg/cm2 have been conducted on five polycrystalline metals, Ni, Ta, Cb, Mo, and W, two brittle single metallic crystals, Sb and Cu5Zn8, and two brittle amorphous materials, ``Melmac 404'' and B2O3 glass. All these materials exhibit ductility at the highest pressure; the largest increases are for the polycrystalline metals of which the largest is W, which breaks brittely at atmospheric pressure but with 81 percent reduction of area at the highest pressure. The shape of the strain hardening curves varies among the five metals from abrupt rise with long tailing off to long gradual rise with comparatively abrupt falling off, in the order W, Mo, Ta, Cb, and Ni. The character of the fracture varies continuously with pressure and is different for the different metals. Of the brittle single crystals Sb has a reduction of area of 55 percent at the highest pressure. The plastic, Melmac 404, gives the smallest increase of ductil...