THE EFFECTS OF HYDROSTATIC-PRESSURE ON THE COMPRESSIVE MECHANICAL-BEHAVIOR OF L12AL3TI-BASED INTERMETALLIC

A Mn-modified L1(2) Al3Ti-base intermetallic was subjected to compressive deformation at room temperature under superimposed hydrostatic pressure's up to 1000 MPa. It is found that its yield strength is essentially unaffected by hydrostatic pressure. The apparent work-hardening rate of true stress-strain curves increases substantially with increasing hydrostatic pressure. Vickers microhardness of pressurized samples always increases with increasing compressive strain, indicating the work-hardening behavior, but it is independent of the superimposed hydrostatic pressure up to 1000 MPa. The density of microcracks (cm/cm2) observed in specimens compressed under hydrostatic pressure increases with increasing compressive strain for each level of pressure. At each constant compressive strain, the corresponding density of microcracks is higher for specimens tested under 170 MPa hydrostatic pressure than that for specimens tested in the 400 to 1000 MPa hydrostatic pressure range. This may imply that besides propagation, the nucleation stage may also be suppressed by a superimposed hydrostatic pressure. It is proposed that both the cataclastic (characteristic for deformation of some rocks) and plastic deformation occur simultaneously during compressive deformation of Ti trialuminides under hydrostatic pressure.