Mechanical behaviour of Al3Ti intermetallic and L12 phases on its basis

The mechanical properties of trialuminide intermetallic Al3Ti and L12 phases Al61Cr12Ti27 and Al66Mn11Ti23 were investigated by an indentation technique. The stress–strain curves were obtained using 9 pyramidal indenters with various angles of sharpening. The hot hardness was measured in the temperature range 20–900 °C, and the plasticity characteristic δH was determined during indentation. Bending tests were used to determine Young’s modulus, and compression tests were carried out as well. The transition of the crystalline structure from tetragonal Al3Ti to cubic L12 of Cr- and Mn doped intermetallics was accompanied by a decrease of hardness over the full range of the investigated temperatures. The temperature dependence of hardness is weak for all investigated intermetallics. The work hardening and mechanism of deformation are discussed. Plasticity characteristic δH for the L12 phases is higher than for Al3Ti and is close to the critical value δH=0.9, which is correlated with bulk ductility, that gives some hope to obtain L12 phases based on Al3Ti with room temperature ductility.