Mechanical behaviour of Al3Ti intermetallic and Ll(2) phases on its basis

The mechanical properties of trialuminide intermetallic Al3Ti and Ll(2) pha ses Al61Cr12Ti27 and Al66Mn11Ti23 were investigated by an indentation techn ique. The stress-strain curves were obtained using 9 pyramidal indenters wi th various angles of sharpening. The hot hardness was measured in the tempe rature range 20-900 degreesC, and the plasticity characteristic delta (H) w as determined during indentation. Bending tests were used to determine Youn g'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 a nd mechanism of deformation are discussed. Plasticity characteristic delta (H) for the L1(2) phases is higher than for Al3Ti and is close to the criti cal value delta (H) = 0.9, which is correlated with bulk ductility, that gi ves some hope to obtain L1(2) phases based on Al3Ti with room temperature d uctility. (C) 2001 Elsevier Science Ltd. All rights reserved.