High-temperature and cyclic corrosion crack resistance of alloys of the Ti-Si-Al-Zr system

We study new alloys of the Ti-Si-Al-Zr system. It is shown that the high-temperature and cyclic corrosion crack-growth resistances of cast materials remain practically constant up to temperatures of 700-800°C and in a 3% NaCl solution (pH = 7), respectively. Annealing and quenching from the ([alpha] + [beta])-and [beta]-phase regions of Ti-4Si-5Al-5Zr cast alloy lead mainly to changes in the structure of the matrix and do not improve its strength and cyclic crack-growth resistance in the investigated working media, except the increase in the threshold of corrosion fatigue after treatment from the [beta]-region and formation of a lamellar [beta]-matrix. The increase in the strength, plasticity, and cyclic crack-growth resistance of these alloys at room and high temperatures is attained as a result of the formation of a globular structure of the matrix and silicide phase after thermomechanical treatment with deformation of at least 90%.