EFFECT OF BASIC PHYSICAL PARAMETERS ON ENGINEERING PROPERTIES OF INTERMETALLICS

Ingots of nickel-rich NiAl were prepared by induction melting under argon, starting with primary materials of technical grade. Sections cut from these ingots were hot-rolled to sheet at 1100 to 1200 C by enclosing them in heavy-walled stainless steel containers. Rolled sheet sufficiently free of defects to enable preparation of mechanical test specimens was obtained. Coldrolling of the hot-rolled sheet can be accomplished at 850 C. Hot-rolled NiAl undergoes a transition to brittle behavior at about 600 C. Below this temperature the mechanical properties are characterized by limited ductility, a sensitivity to surface notches, and by a flow stress that is relatively invariant in respect to temperature. Above 600 C, ductility increases markedly, sensitivity to surface conditions diminishes, and the flow stress becomes strongly temperature dependent. Single crystals do not exhibit a transition in mechanical behavior and are much weaker and more ductile than polycrystalline materaial at temperatures below 800 C. (Author) Report on Refractory Inorganic Non-Metallic Materials.