Production of aluminum-based L12 compounds and their mechanical properties

In the first part, trials have been made to modify the structure of Al3V from the D0(22) to the L1(2) by substituting a part of Al by six transition metals. Unlike the case of Al3Ti, the modification was not successful in any case. In the second part, single crystals of Ni-modified Ll(2)-Al3Ti and those of (Ni, Cr)-modified L1(2)-Al3Ti have been compressed at high temperatures. In the ternary compounds, the critical resolved shear stress (CRSS) is higher than 180MPa up to 1000degreesC showing the yield stress anomaly in an intermediate temperature range, while CRSS of the quaternary compound decreases monotonically from 210MPa at room temperature to 100MPa at 1000degreesC. Below 600degreesC, the ductility was limited in every compound possibly due to the presence of hard and brittle second phase particles.