MECHANISMS OF CYCLIC DEFORMATION OF NIAL SINGLE-CRYSTALS AT HIGH-TEMPERATURES

被引:23
作者
BUSSO, EP [1 ]
MCCLINTOCK, FA [1 ]
机构
[1] MIT, DEPT MECH ENGN, CAMBRIDGE, MA 02139 USA
来源
ACTA METALLURGICA ET MATERIALIA | 1994年 / 42卷 / 10期
基金
美国国家科学基金会;
关键词
D O I
10.1016/0956-7151(94)90459-6
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Cubic-oriented NiAl single crystals were subjected to epsilon = epsilon(m) +/- 0.5% cyclic strain histories at 750 and 850-degrees-C. For epsilon(m) = 0%, the material initially strain-softened with re-arrangement of the dislocation structure. Stable cyclic responses revealed predominantly kinematic hardening for epsilon = +/- 0.5%, and isotropic hardening during monotonic deformation of 35%. The types of interactions between gliding and forest dislocations from the active slip systems, viz. {110}[110], were studied based on an idealization of the dislocation configurations observed in TEM foils. The total slip plane glide resistance was found to be mainly due to lattice resistance and to forest dislocations, almost-equal-to 70% of which were found to be impenetrable. An idealized model of the dislocation network revealed that appreciable plastic flow (i.e. >0.01%) requires obstacle bypassing. Bypassing results in the formation of dipoles in gliding screw dislocations which contribute to kinematic hardening. As dislocations travel larger distances for epsilon > 0.5%, they develop [111] sessile segments and tangles and the dislocation density increases beyond the 3 mum-2 needed to balance recovery, to 13.8 mum-2 at epsilon(m) = 35%, within 3% of that predicted by the model.
引用
收藏
页码:3263 / 3275
页数:13
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