ELECTRON-MICROSCOPY AND DIFFRACTION OF ORDERING IN NI-W ALLOYS

被引:19
作者
MISHRA, NS [1 ]
RANGANATHAN, S [1 ]
机构
[1] INDIAN INST SCI, CTR ADV STUDY, DEPT MET, BANGALORE 560012, KARNATAKA, INDIA
来源
ACTA METALLURGICA ET MATERIALIA | 1995年 / 43卷 / 06期
关键词
D O I
10.1016/0956-7151(94)00417-X
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Electron microscopy and diffraction studies of ordering in stoichiometric Ni-20%W and off-stoichiometric Ni-15%W alloys have been carried out. The specimens of Ni-20%W were first disordered at 1398 K for 4 h and then quenched rapidly into water. Short range order (SRO) spots were observed at {1 1/2 0}* positions. Two hitherto unknown metastable phases: D-2h(25)-Ni2W and DO22-Ni3W were observed in the diffraction patterns. Long range order (LRO) transformations were studied at 1103 and 1213 K. Kinetics and mechanism of transformations have been identified. Ni-15%W specimens were solution treated at 1523 K for 1 h followed by quenching in water. SRO spots similar to those found in Ni-20%W were observed in this alloy as well. The transition to LRO was studied at 1093 K. Distinct Ni4W precipitates could be observed after 5 h of annealing at this temperature. After 100 h of annealing precipitates were found to grow into faceted shape coherent with the disordered matrix. After prolonged annealing for over 150 h the Ni4W precipitates began to lose coherency by the generation of misfit dislocations. The microstructural observations have been compared for the stoichiometric and off-stoichiometric alloys.
引用
收藏
页码:2287 / 2302
页数:16
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