Criticality in the plastic deformation ofNi3Al

It is argued that the critical point of a nonequilibrium phase transition in the motion of dislocations results in the experimentally observed power-law creep rates in ${\mathrm{Ni}}_3$Al and related intermetallic alloys. A simple scaling argument is used to connect the critical exponents of the transition directly to the creep rate. A model of dislocation motion is constructed. The exponents predicted from the model are in agreement with those deduced from creep experiments.