Viscoplastic alloys
Hardness of bodies - Analysis of other behaviors

Scientists were quick to point out that the hardness of a metal alloy at high temperature decreases as the duration t of application of force P increases, and obtained empirical relationships of the type [47]:

The coefficients M and m _app depend on temperature and test conditions; the factor m _app, which we'll call apparent viscosity index, is a priori directly related to the viscosity index of the material. But, unlike hardness tests on metals carried out far below the melting temperature, these results have only gradually...