Study of indentation microhardness of bismuth-doped As2Se3 glasses

The experimental results of an investigation of the load dependence of microhardness of the surfaces of samples of (As1-xBix)(2)Se-3 glasses with x <= 0.1 wt fraction are described and discussed. It was observed that, with an increase in indentation diagonal d, the microhardness H-V of the samples first increases (reverse indentation size effect; reverse ISE), then decreases showing a maximum hardness H-max (normal ISE), and finally increases again after attaining a minimum hardness H-min (reverse ISE). The experimental data in the former two regions were analyzed by using the relation H-V = H-0(1+d(0)/d), where H-0 is the load-independent hardness of a sample and the parameter d(0) is related to elastic and plastic deformation of the sample. It was found that the load-independent H-0 for the samples initially increases up to maximum value (for x = 0.025) and then decreases with increasing Bi content x in these regions. These results are attributed to changes caused by Bi additive in the structure of flow defects participating in plastic deformation of the (As1-xBix)(2)Se-3 samples.