In this paper, the results of creep and stress-rupture tests on Ni3Al base γ′ monocrystals are presented. The results show that the steady state creep rate εs conforms to the relationship: εs=Cσmexp(-Qc′/RT). The exponent m depends only on temperature. m(850℃)=3.95, m(950℃) = 3.62. The apparent activation energy of creep Qc′ amounts to 88 k cal/g-at. for Ni3Al crystals. All of the alloying elements studied Ti, Nb and W raise Qc′, the effect of Nb being the greatest, while W proves to be most effective in improving the creep strength. The orientation of crystals has a marked influence on εs. oriented crystals have the lowest εs and the longest stress-rupture life tr. tr≥ 100 hr for T= 1050℃ and σ= 5 kg/mm2. The Monkman-Grant relation tr(εs)p=const. holds likewise for Ni3Al single crystals, with p = 0.82.The glide system of γ′ crystals in creep appears to be {111} .
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