Permanent Joint Stability of Heat-Resistant Deformable Nickel and Cast Intermetallic Alloys Obtained under Superplasticity Conditions: Part 1

摘要

In this paper, we study the welded joints of cast intermetallic single-crystal rhenium-containing alloy VKNA-25 with crystallographic orientation [001] and deformable disk heat-resistant nickel alloy EP975 depending on the parameters (temperature and degree of deformation) of pressure welding under superplasticity conditions. The samples before and after heat treatment (annealing at 1210°C for 5 h) are compared. The results of X-ray spectral microanalysis of a solid-phase joint in the welding zone and at distances of up to 140 μm are presented in comparison with the initial chemical composition of the alloys, indicating an intense course of diffusion processes. The obtained results are analyzed from the point of view of maintaining the balance of alloying that is calculated by the method of G.I. Morozova (calculating the number of valence electrons per unit atomic mass of the composition). The change in the atomic mass and average electron concentration of solid-phase compounds before and after heat treatment in the welded joint zone and at distances of up to 140 μm is calculated. Calculated with allowance for the alloying balance, the alloy compositions are shown to allow obtaining a high-quality one-piece connection of a disk and a blade for blisk-type structures that is performed under superplasticity conditions using a setup for high-temperature pressure welding.