Stability of composite materials NiAl-refractory metal with cellular structure

The structure and mechanical properties of NiAl-Wand NiAl-W-Mo composite materials (CM) obtained by sintering from powders are studied. Comparative analysis of the effect of hot compressive deformation of a compact material at 1000–1300°C on the integrity of the microspecimens and of the tungsten shells on NiAl granules in CM with cellular structure is performed. The thermokinetic stability of the grain structure of unalloyed nickel aluminide NiAl and of a NiAl-W composite material with cellular structure is investigated. The temperature of the beginning of recrystallization of the NiAl intermetallic is determined. A map of structural states is plotted in the “temperature-operating time” coordinates for CM with cellular structure. The local chemical composition of the “NiAl-refractory metal” phase boundary is studied in CM with cellular structure and without it. The effect of the structural state of CM on the yield strength in compressive tests at 1000°C is determined. The oxidation resistance at 1000–1300°C is studied and a treatment approaching the oxidation resistance of CM with cellular structure at 1000–1300°C to the level of high-temperature strength of unalloyed NiAl and of its alloy with 4 wt.% Hf is suggested. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 25–30, June, 2006.