Effect of the method of production of an Ni3Al/Mo layered composite material on its structure and properties

A stack of alternating 25 100-μ-thick Ni₃Al plates and 28 200-μm-thick Mo plates is subjected to hot isostatic pressing (HIP) at a temperature T = 1200°C and a pressure P = 150 MPa for τ = 2.5 h followed by hot rolling at 1050–950°C to a thickness of 2.3 mm. The stack is then subjected to cold rolling (CR) to a thickness of 0.5 mm without intermediate annealing, subsequent annealing during HIP at T = 1200°C, P = 150 MPa, and τ = 2.5 h, and CR to a thickness of 0.22 mm. Upon CR at a strain ε changing from 80.8 to 95.8%, the following specific structure forms in the longitudinal direction: molybdenum layers acquire a wavelike structure, can contact with each other, form “cells,” and retain almost the same thickness, and Ni₃Al alloy layers are rejected between the molybdenum layers to form a regular structure made of alternating thickenings and thinnings across the rolling direction. Annealing during HIP and subsequent CR to ε = 98.2% lead to the formation of zones with a broken alternation of layers in the longitudinal and transverse directions, which is related to different strain resistances of the (more refractory) molybdenum and Ni₃Al layers at 20°C. The adhesion between the layers is good, and no intermediate phases form at the interface. The ultimate bending strength of the 2.3-mm-thick workpiece at 20°C is 1000 ± 100 MPa, and the prepared material has a plasticity margin.