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A crystalLOGRAPHIC MODEL FOR THE ORIENTATION DEPENDENCE OF LOW CYCLIC FATIGUE PROPERTY OF A nickel-base single crystal superalloy

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Applied Mathematics and Mechanics(English Edition) 2000年第4期21卷 415-424页

作者：岳珠峰陶仙德尹泽勇李海燕 Department of Applied Mechanics Northwestern Polytechnical University Xi'an P R China Aeronautical Department 608 Institute Zhuzhou P R China

Fully reversed low cyclic fatigue (LCF) tests were conducted on [0 0 1], [0 1 2], [(1) over bar 1 2], [0 1 1] and [(1) over bar 1 4] oriented single crystals of nickel-bared superalloy DD3 with different cyclic strain rates at 950 degrees C. The cyclic strain rates were chosen as 1.0 x 10(-2), 1.33 x 10(-3) and 0.33 x 10(-3) s(-1). The octahedral slip systems were confirmed to be activated on all the specimens. The experimental result shows that the fatigue behavior depends an the crystallographic orientation and cyclic strain rate. Except [0 0 1] orientation specimens, it is found from the scanning electron microscopy(SEM) examination that there are typical fatigue striations on the fracture surfaces. These fatigue striations are made up of cracks. The width of the fatigue striations depends on the crystallographic orientation and varies with the total strain range. A simple linear relationship exists between the width and total shear strain range modified by an orientation and strain rate parameter. The nonconformity to the Schmid law of tensile/compressive flaw stress and plastic behavior existed at 95 degrees C, and an orientation and strain rate modified Lall-Chin-Pope ( LCP) model was derived for the nonconformity. The influence of crysrallographic orientation and cyclic strain rate on the LCF behavior can be predicted satisfactorily by the model. In terms of an orientation and strain rate modified total strain range, a model for fatigue life was proposed and used successfully to correlate the fatigue lives studied.

关键词： nickel-base single crystal superalloy low cyclic fatigue crystallographic orientation dependence strain rate cyclic plastic creep life crystallographic plastics

Oxidation behavior of 4774DD1 Ni-based single-crystal superalloy at 980℃ in air

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China Foundry 2024年第2期21卷 116-124页

作者： Yu Fang Ya-zhou Li Qiang Yang Qun-gong He Xiu-fang Gong Qian Duan Hai-yang Song Fu Wang Qiong-yuan Zhang Hong Zeng State Key Laboratory of Long-Life High Temperature Materials Dongfang Turbine Co.Ltd.Deyang 618000SichuanChina State Key Laboratory for Manufacturing System Engineering School of Mechanical EngineeringXi’an Jiaotong UniversityXi’an 710049China

The oxidation behavior of a novel Ni-based single-crystal 4774DD1 superalloy for industrial gas turbine applications was investigated by the isothermal oxidation at 980℃ and discontinuous oxidation weight gain *** phase constitution and morphology of surface oxides and the characteristics of the crosssection oxide film were analyzed by XRD,SEM and *** show that the oxidation kinetics of the 4774DD1 superalloy follows the cubic law,indicating its weak oxidation resistance at this *** the oxidation time increases,the composition of the oxide film evolves as following:One layer consisting of a bottom Al_(2)O_(3)sublayer and an upper(Al_(2)O_(3)+NiO)mixture sublayer after oxidized for 25 ***,two layers composed of an outermost small NiO discontinuous grain layer and an internal layer for 75 *** internal layer is consisted of the bottom Al_(2)O_(3)sublayer,an intermediate narrow CrTaO_(4)sublayer,and an upper(Al_(2)O_(3)+NiO)mixture *** two layers comprising an outermost relative continuous NiO layer with large grain size and an internal layer as the oxidation time increases to 125 *** internal layer is composed of the upper(Al_(2)O_(3)+NiO)mixture sublayer,an intermediate continuous(CrTaO_(4)+NiWO_(4))mixture sublayer,and a bottom Al_(2)O_(3)***,three layers consisting of an outermost(NiAl2O_(4)+NiCr2O_(4))mixture layer,an intermediate(CrTaO_(4)+NiWO_(4))mixture layer,and a bottom Al_(2)O_(3)layer for 200 h.

关键词： nickel-base single crystal superalloy oxidation kinetics oxide film microstructure mechanism

Influence of Co, W and Ti on the Stress-rupture Lives of a single crystal nickel-base superalloy

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Journal of Materials Science & Technology 2006年第2期22卷 169-172页

作者： Dayun YANG Tao JIN Nairen ZHAO Zhihui WANG Xiaofeng SUN Hengrong GUAN Zhuangqi HU Department of superalloy Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

The influence of Co, W and Ti on stress-rupture lives of a Ni-Cr-AI-Mo-Ta-Co-W-Ti single crystal nickel-base superalloy has been investigated using a L9 （34） orthogonal array design （OAD） by statistical analysis. At a selected composition range, Ti content was the most important factor to the effect of the stress-rupture lives and then followed by Co content. W content had the minimum effect on stress-rupture lives. The optimal alloy should contain 10 wt pct Co, 8 wt pct W and zero Ti. The optimized alloy also had good microstructural stability during thermal exposure at 870℃ for 500 h.

关键词： nickel-base single crystal superalloy Orthogonal array design Stress-rupture