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STUDY OF TCP PHASE PRECIPITATING IN GH4199 SUPERALLOY 总被引:3,自引:0,他引:3
T.Cui Y.S.Zhang S.W.Guo L.Wang H.C.Yang 《金属学报(英文版)》2004,17(5):645-650
The precipitating regulation and mechanism of TCP phase (μ phase and σ phase) are studied, using electron hole number (EHN) theory, phase analysis technology and TEM observation. The results indicate that the EHN in studied alloy is 2.311-2.348 which is higher than that of critical EHN of μ phase precipitate (2.30), so μ phase could precipitate if there is enough thermo-expasition. In contrast, the calculated EHN is less than that of critical EHN of σ phase precipitate (2.52). However the σ phase is also observed by TEM.Enrich of Cr and Mo around γ phase after γ‘ phase precipitated leads to σ phase precipitated. 相似文献
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ZHANG Yuanhu SUN Jian XIANG Yi HU Gengxiang Shanghai Jiaotong University Shanghai ChinaLI Tiefan Institute of Corrosion Protection of Metals Academia Sinica Shenyang China Yuanhu Department of Materials Science Engineering Shanghai Jiaotong University Shanghai 《金属学报(英文版)》1991,4(2):118-122
Studies on the high temperature creep and fracture behaviours in air or in SO_2 contaminatedenvironment for the Fe-base superalloy GH302 with flat or zigzag grain boundaries(GB)and the Ni-base superalloy Rene 80 were carried out.Although the creep rupture propertiesof the GH302 with zigzag GB was remarkably superior to that of flat GB in air,the propertiesof both droped dramatically in 10% SO_2-air environment,the creep rupture properties of thedirectional solidified Rene 80 were much better than that of the conventionally cast alloy inair,and also kept the same property in SO_2 contaminated environment as in air.Owing to theinteraction between creep and sulphidation,the failure mechanism relates to the formation ofmolten Ni-Ni-3S_2 eutectic along GB,led to the premature failure of the alloy. 相似文献
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新型Ni-Co基高温合金中平衡析出相的热力学研究 总被引:2,自引:0,他引:2
利用热力学计算软件JMatPro和相应的镍基高温合金数据库,研究了U720Li合金以及在此基础上研发的新型Ni-Co基高温合金的化学成分对平衡相的析出行为、加工性能和γ/γ′晶格错配度的影响.结果表明:Ti/Al值(原子比)的增加提高了合金中γ/γ′相的晶格错配度,γ′析出相的含量随Ti+Al含量(原子分数)的增加而增加.因此,增加Ti/Al值和Ti+Al含量能提高合金的高温强度.Co含量的升高可以拓宽合金的加工窗口,改善合金的加工能力,并且还可以增加合金γ/γ′相的晶格错配度,提高合金错配强化的效果.同时,Ti/Al值的增加促进合金中η相析出,而Co含量的增加具有抑制η相的效果.因此,在Co含量较高的Ni-Co基高温合金中,适当提高Ti含量,增加Ti/Al值对提高合金高温强度有利. 相似文献
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NANO SIZE EFFECT IN GRAIN BOUNDARY MIGRATION OF COPPER 总被引:1,自引:0,他引:1
L.Zhou X.Q.Wei N.G.Zhou D.G.Li 《金属学报(英文版)》2004,17(1):11-15
Molecular dynamics simulations of high temperature annealing of copper bicrystals have been carried out. The bicrystals have planar grain boundaries, and the gain size varies in nano range. An EAM (embedded atom method) potential of FS type is used for calculating the interatomic forces. The results show that in nanocrystalline copper, GB migration driven by inter-GB reaction can take place. A critical grain size is identified, below which the inter-GB reaction becomes strong enough to trigger GB motion, which accelerates rapidly and leads to annihilation of the grain boundaries. The critical size is found to be 16 atomic radii. A “through intermediate grain mechanism“ is identified for the nano-grain boundary motion observed, which is never reported for GB migrations of conventional polycrystalline metals. 相似文献
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掺杂硫对IN718合金性能的影响 总被引:1,自引:0,他引:1
研究了掺杂硫对IN718合金的影响,结果表明,硫使蠕变抗力和持久寿命降低,硫对IN718合金的有害作用具有明显的表面效应,一种可能的机制是硫加剧表面晶界在蠕变和持久试验中的氧化和开裂。 相似文献
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GRAINBOUNDARYSEGREGATIONANDINTERGRANULARBRITTLENESSINHIGHSTRENGTHALUMINIUMALLOY¥Song,Renguo;Zheng,Meiguang(DeparrmentofMateri... 相似文献
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金属晶界在高温氧化中的作用 总被引:19,自引:1,他引:18
李铁藩 《中国腐蚀与防护学报》2002,22(3):180-183
扼要阐述了金属材料晶界在纯金属与合金高温氧化中的 作用.指出金属中晶界面积增加(晶粒尺寸减小)有3种效应:改善合金抗氧化性能的有益的正 效应,相反为负效应以及双重效应.讨论了金属晶界扩散动力学基本方程的参数,如Tamman 温度及晶粒尺寸对其影响、晶粒形状因子(q)、晶界偏聚因子(s)、晶界夹角(θ)对晶界 扩散的影响.最后介绍了晶界作为高速扩散通道对合金晶间内氧化的重要作用. 相似文献
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EFFECTSOFTHREEDIMENSIONALDIRECTIONOFSECONDDENDRITEONCOMPETITIVEGRAINGROWTHINDD8SUPERALLOYLiuZhiyi;WeiPengyi;FuHengzhi(StateKe... 相似文献
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Ni3Al晶界结构的计算机模拟 总被引:2,自引:0,他引:2
本文运用嵌入原子法势函数和静态弛豫最陡梯度的计算方法,模拟[100],[110]和[111]轴一系列具有不同晶界几何参量及化学成分的Ni_3Al对称倾侧晶界原子结构、晶界能和晶界的内聚能、电荷密度分布及应力场等内容,并着重研究和讨论了它们与硼偏聚,Ni_3Al的晶界韧脆行为,特别是硼韧化的化学计量效应之间的关系。 相似文献
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