Structure and properties of melt-spun Al-Zr-Ti alloys III. Phase transformations at elevated temperatures

Rapidly solidified Al-Zr-Ti alloys are far from thermodynamic equilibrium. Electrical resistance measurements revealed two stages of microstructure ch anges occurring at elevated temperatures. Using the results of X-ray diffra ction analysis the first stage was explained by the precipitation of the me tastable Al-3(ZrxTi1-x) phase with L1(2) structure and the second stage by the formation of the stable Al-3(ZrxTi1-x) phase with DO23 or DO22 structur e. Ti atoms substitute for Zr atoms in the lattices of these phases. This s ubstitution improves the lattice mismatch between the particles of the Al-3 (ZrxTi1-x) phase and the matrix and shifts the individual decomposition sta ges to higher temperatures. Consequently, a better structure and strength s tability may be expected.