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41.
42.
基于镍基单晶合金蠕变过程中的细、微观组织结构变化及损伤特点,本文建立了考虑材质劣化和空洞损伤的双参数蠕变损伤本构方程及寿命预测模型。利用DD3单晶材料〈001〉晶体取向的760,850和1000℃实验结果考核表明,所建模型可以比较准确地预测蠕变第二、第三阶段变形状态及破坏特征。第二阶段持续时间、第三阶段开始时间可以表示成蠕变应力的指数函数;随着温度的升高,材料劣化加剧,空洞损伤也增加。 相似文献
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Ni-Cr-Al纳米晶合金在1000℃的高温氧化行为 总被引:5,自引:0,他引:5
研究了纳米晶Ni-Cr-Al合金的高温氧化行为,发现与
铸态合金不同,随成分不同纳米晶合金在1000℃氧化时,氧化物可分为四个区:A单一Al2O3区;B复杂氧化膜含一连续Al2O3内层区; C复杂氧化膜含内氧化物区;D Al2O3和NiAl2O4共生区.纳米晶化明显扩展了Al2O3生成区的成份范围. 相似文献
45.
SUN Liling DONG Lianke ZHANG Jishan TANG Yajun ZHANG Jinghua HU Zhuangqi Institute of Metal Research Academia Sinica Shenyang China SUN Liling Institute of Metal Research Academia Sinica Shenyang China 《金属学报(英文版)》1993,6(5):291-295
The morphology of solid/liquid interface of a directionally solidification process is describedby means of fractal analysis,and the relations among the fractal dimension of the solid/liq-uid interface,solidification rate,dendrite arm space and the phosphorus content of the test al-loys have been given.It was found that the increase of the solidification rate and the phos-phorus content of the test alloy will lead to a increase,following the regularity of exponentialfunction,in the fractal dimension of solid/liquid interface.Furthermore,by combining thefractal theory and the thermodynamic principle with the measured results,it has been provedthat the fractal dimension is not only a kind of simple geometrical parameter used in des-cribing irregular geometry,but also a state function depending the change of solidificationparameters and chemical compositions. 相似文献
46.
S. Y. Chang Y. T. Hung T. H. Chuang 《Journal of Materials Engineering and Performance》2003,12(2):123-127
Alumina ceramics were brazed to Inconel 600 and UMCo-50 superalloys at 900 °C for 10 min using an Sn10Ag4Ti active filler
metal. The brazing filler showed good wettability on alumina and superalloys. The flexural strengths were 69 and 57 MPa for
alumina/Inconel 600 and alumina/UMCo-50 joints, respectively. In both cases, the brazed specimens fractured along the Sn10Ag4Ti/superalloy
interfaces after four-point bending tests. Electron probe microanalysis (EPMA) elemental mapping revealed that the Ni of Inconel
600 and the Co of UMCo-50 dissolved into Sn10Ag4Ti filler metal, which serves to reinforce the weak Sn10Ag4Ti matrix. 相似文献
47.
对12Cr1MoV和0Cr17ni12Mo2两种管材的镍基异种金属接头进行焊后状态和高温运行后状态对比试验。结果表明,高温运行使异种钢接头σ-ε图中曲线移动,反映了高温运行后异种钢接头的屈服强度和塑性有所下降;高温运行使异种钢接头的各项力学性能指标σb,σ0.2,δ5,ψ均略有下降,该结果与接头组织变化及12Cr1MoV钢珠光体组织中碳化物球化倾向等不利因素有关;高温运行对异种钢接头断口部位及宏观断口形貌特征无大的影响;高温运行后异种钢接头拉伸试样仍断在母材处,表明镍基异种钢接头的抗拉强度是比较满意的。 相似文献
48.
Ajay K. Misra 《Oxidation of Metals》1986,25(3-4):129-161
The hot corrosion of a nickel-base superalloy, Udimet 700, has been studied in the temperature range 900–950°C. The effect of the amount of Na
2SO4 on the corrosion kinetics was determined. Large weight gains and severe corrosion were associated with two different modes of degradation: (1) formation of large, interconnected sulfides beneath the external scale, and (2) formation of a Na2MoO4-MoO3 melt. The corrosion due to formation of the Na2MoO4-MoO3 melt occurred for all the salt-coating thicknesses, whereas, large sulfides were formed only for the heavier coatings of Na2SO4. The formation of Na2MoO4-MoO3 melt required an induction period, and the length of the induction period was observed to be a function of the amount of Na2SO4 and of temperature.Work funded under NASA Grant NCC 3-43. 相似文献
49.
KarinGraf AnaSofiaC.M.d'Oliveira 《材料热处理学报》2004,25(5):152-156
Degradation phenomena like wear and corrosion, may have their effects accelerated as components operate at high temperature. The aim of this work is to make an indirect evaluation of the influence of high temperature exposure on wear behavior of Ni coatings. A Ni-Cr-Mo-W alloy, was deposited with Plasma Transferred Arc (PTA) process. An indirect approach based on the Ahrrenius relationship was used to evaluated long time exposures at high temperatures. To simulate longer exposures at lower temperatures, coatings were exposed to higher temperatures for the same time interval. So coatings were soaked in an air furnace at 650℃, 1000℃ and 1200℃. Metal/metal wear behavior was evaluated by pin-on-disc tests. Pins were removed from the coatings by eletrodischarge machining and rubbed against a VC31 quenched and tempered tool steel. Two sets of wear tests were run at 2m/s, for different loads (0.5, 1.0, 2.0 and 3.0Kg) and for different sliding distances (120, 720, 1080, 1440 and 1800m).Coatings characterization was done by scanning electronic microscopy and Vickers microhardness. Results showed as temperature is increased, coatings wear performance is altered,and this is associated with microstructural changes. 相似文献
50.