Structural features of powder materials operating under high temperatures, stresses, and wear

Abstract

It is known that parts of hot zones of metallurgical plants as well as heavily loaded pressing and forging tools operate under a high temperature, elevated mechanical stresses, the action of a steam ambient, slag, surface wear due to contact with the hot metal, etc. The possibility of providing the requisite properties by using high-temperature alloys has already been exhausted because the complexity of their composition intensifies the segregation inhomogeneity of the ingots which cannot be eliminated in the process of hot deformation and homogenizing annealing. As a rule, fracture starts under the conditions of cyclic loads on local structural defects such as accumulations of coarse particles of the eutecie γ′-phase, borides, carbides, nonmetallic inclusions. The chemical inhomogeneity and the structural defects caused by it can be removed by using methods of powder metallurgy that can provide materials with unique properties unattainable in the conventional metallurgy. The present paper is devoted to the special features of the structure of powder nickel alloys.