Instabilité et localisation de la déformation dans les monocristaux C.F.C.

Instability and flow localization in F.C.C. single crystals

Institut des Recherches métallurgiques Académie polonaise des Sciences, Cracovie

Abstract

Single crystals of copper, aluminium and nickel oriented for single and multiple slip have been deformed in a tensile test at room temperature. The actual stress-strain curves and the plots of the slope da/dr versus the stress have been reported also beyond the necking point [math].

It has been found that for single crystals oriented in <112> direction at the onset of instability the [math] versus a curves beyond the necking point changes from a steeply decreasing slope into a horizontal branch. For <111> orientation only, the [math] versus a curves develop a straight branches which are identical with the extrapolated ones in the range of [math].

Shear bands from when the condition [math] is reached. Based upon the TEM and X-ray diffraction results, the formation of the shear bands has been related to the activation of the coplanar slip systems.