Solid-phase joining of the cast intermetallic Ni₃Al-based alloys and wrought nickel-based superalloys via using superplastic deformation

The paper summarizes the results of solid-phase joining experiments performed for intermetallic single-crystal Ni₃Al-based alloys (known as Russian VKNA-alloys) and wrought fine grained nickel-based superalloys using superplastic deformation of the wrought superalloys. For this, two single-crystal VKNA-alloys, VKNA and VKNA-25 and two Russian nickel-based superalloys, EK61 and EP975, were taken. It was shown that the formation of an ultrafine grained structure (d<1 µm) in the EK61 superalloy made it possible to obtain the solid-phase joint of EK61/VKNA under pressure welding at T = 800 °C using superplastic deformation of the nickel-based superalloy. Another nickel-based superalloy, EP975, was taken in a fine grained condition (d = 8 µm). High-quality solid-phase joints of EP975/VKNA and EP975/VKNA-25 were obtained under pressure welding at T = 1125 °C using the superplastic deformation of the EP975 superalloy. The obtained solid-state joints EP975/VKNA and EP975/VKNA-25 were subjected to heat treatment, which led to the formation of coarse γ grains in the EP975 superalloy. This also led to an increase in thickness of the γ phase interlayers up to 500 nm in both VKNA-alloys near the solid-phase joints (paper)