BEND-DUCTILITY, CREEP STRENGTH AND PHYSICAL-PROPERTIES OF EXTRUDED CHROMIUM-MODIFIED AL3TI

Chromium-modified Al3Ti (Al-8Cr-25Ti, at.%) with the cubic L1(2) structure was processed by extrusion, resulting in a fine-grained recrystallized microstructure. The material was essentially single phase, with only a low volume fraction of Al2O3 and titanium-enriched particles. Oxygen and carbon contents were also low. Room temperature bend tests with strain gages attached to the tension side of the specimens were performed. For sufficiently good surface finishes permanent tensile strains up to 0.16% were recorded, in qualitative agreement with Zhang's results (S. Zhang, J. P. Nic and D. E. Mikkola, Scr. Metall., 24 (1990) 57). However, for less perfect finishes, fracture occurred well below the compressive yield stress. In other words, Al-Cr-Ti is highly notch-sensitive and has a low toughness. As in other trialuminides, fracture occurred by cleavage. Compression creep tests at 1200 K, measurements of Young's modulus, the thermal expansion coefficient, the melting point and the specific heat capacity have been performed.