A correlation between changes in the micro-hardness, and dislocation mobility in the stress field of an indentor, was identified in Pb-doped crystals that had been subjected to aging and quenching. It was attributed to the effect of impurity defects upon the double cross-glide of screw dislocations.

J.S.Boyarskaya, R.P.Zhitaru, N.A.Palistrant: Fizika Tverdogo Tela, 1995, 37[7], 2189-94 (Physics of the Solid State, 1995, 37[7], 1192-5)