INFLUENCE OF HEAT TREATMENT ON THE STRUCTURE AND MECHANICAL PROPERTIES OF Ni_3Al - BASED ALLOYS

摘要

Two Ni_3Al - based intermetallic alloys with additions of zirconium, boron and chromium of different content were investigated. Long lasting annealing (up to 100 hours) at 1000 degree and 1200 Celsius degree in air or argon atmospheres leads to gradual homogenizing. A higher level of homogeneity of cast chromiumlees, alloy was obtained in comparable conditions of heat treatment. It was stated that annealing temperature has essential influence on homogenization process of the investigated alloys, much more essential than time of annealing and environmental conditions. Those conditions of treatment are critical for microstructure and properties of investigated alloys. For matched conditions of plastic working an optimum level of strain hardening was received. This did not cause a loss of cohesion of investigated alloys but was sufficient to conduct a recrystallization process. It was pointed out that fine - grained structure of both investigated alloys was responsible for their mechanical properties improvement.