LI Gang
,
WANG Zhongguang
,
LI Guangyi(State Key Laboratory of Fatigue and Fracture for Materials
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China)V.OVCHARENKO(Institute of Strength Physics and Materials Science
,
Russian Academy of Science
,
Siberian Branch
,
Tomsk
,
Russia) Manuscript received 3 May 1995
金属学报(英文版)
Self propagating high temperature synthesis(SHS) under compression was utilized to obtain an intermetallic compound Ni_3 Al by using elemental powders.The microstructure of the SHS product was observed by optical microscopy(OM) and scanning electron microscopy(SEM).The results reveal that the SHS Ni3Al is a single-phase polycrystalline alloy wilh LI2 crystal structure.Tensile tests were conducted from room temperature to 800℃ both in air and in vacuum.The results show that the SHS Ni_3Al exhibits an anomalous temperature dependence of ultimate tensile strength.The ultimate tensile strength in vacuum is much higher than that in air over the whole temperature range.Fracture surfaces are characterized by the brittle grain boundary fracture and the intergranular fracture mode can not be affected markedly by the test environment.
关键词:
:Ni_3Al
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Sergey N.Kulkov Alexander G.Melnikov Institute of Strength Physics and Materials Science
,
The Russian Academy.of Science
,
Siberian Branch
,
Tomsk
,
634055
,
RussiaYanchun ZHOU Shengqi CHEN Zhe QU Institute of Metal Research
,
Academia Sinica
,
Shenyang
,
110015
,
China
材料科学技术（英文）
The effects of shock loading on the morphology,grain growth during heating and phase transforma- tion of ZrO_2 have been investigated.It is shown that shock loading may be efficiently used to modify submicron ceramic powders with nanocrystalline structure.After shock loading,the critical diameter of ZrO_2 particles transformed from tetragonal to monoclinic decreased due to stored strain energy. Annealing of powders resulted in reversible transformation to the tetragonal without considerable grain growth up to 1200℃.
关键词:
submicron ceramics
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