SUN Zhongxi W. Forsling CHEN Jin Division of Inorganic Chemistry
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Lulea University of Technology
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S-951 87 Lulea
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SwedenDept.of Mineral Engineering
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Central South University of Technology
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Changsha
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410083
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ChinaTo whom correspondence should be addressed
材料科学技术（英文）
The complexation of phosphates in the quartz-metal ion-H_2O-oleate system was studied. Computer assisted calculations with the aid of the advanced program SOLGASWATER and known equilibrium constants were used to evaluate the mechanism,The calculation results revealed that in the presence of a certain amount of phosphates, metal ions adsorbed at the quartz-H_2O interface will be transferred into solution.Thus the competi- tion for metal ions between phosphates and the quartz surface leads to surface deactivation and re- duced floatability.Various distribution diagrams clearly demonstrate the change of surface complexation as a function of added phosphate concentration.The deactivation products were also evaluated.
关键词:
complexation
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null
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null
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null
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null
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null
于金江
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孙晓峰
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侯贵臣
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金涛
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管恒荣
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胡壮麒
钢铁研究学报
测试了3种镍基合金和1种定向钴基高温合金矩形缺口试样的热疲劳行为.试样缺口处萌生裂纹的扩展长度作为热循环次数的函数.实验结果表明:新型镍基导向叶片材料M951合金的热疲劳裂纹萌生速率和裂纹扩展速率最低.M951合金的热疲劳裂纹主要沿晶内枝晶间扩展,主裂纹生长以裂纹尖端连续开裂的形式进行.
关键词:
M951
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热疲劳
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裂纹
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萌生速率
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扩展速率
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导向叶片
夏鹏成
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禹文芳
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于金江
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孙晓峰
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管恒荣
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胡壮麒
材料工程
doi:10.3969/j.issn.1001-4381.2007.12.002
研究了定向凝固DZ951镍基高温合金在长期时效过程中的组织演化.结果表明:随着时效温度和时间的增加,γ′粗化形筏.形筏时间随时效温度的升高而减少.形筏驱动力为弹性应变能和界面能的降低.γ′长大受元素扩散控制,长大遵循LSW理论,长大激活能为294kJ/mol左右.由于DZ951合金γ′相中含有较多的高熔点元素W,Mo和Nb等,从而提高γ′相的稳定性,增加γ′长大激活能.合金在长期时效过程中未出现拓扑密排相(Topological Close-Packed Phase, TCP Phase)等有害相,表明DZ951合金具有较好的组织稳定性.
关键词:
DZ951合金
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长期时效
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γ′相
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形筏
夏鹏成
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于金江
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孙晓峰
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管恒荣
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胡壮麒
稀有金属材料与工程
研究了不同上限温度对DZ951合金热疲劳性能的影响.结果表明:随着上限温度的升高,热疲劳裂纹扩展速率增加,合金的热疲劳抗力降低.DZ951合金经热处理后,热疲劳性能提高.合金主要通过氧化产生孔洞,孔洞相互连接使热疲劳裂纹萌生和扩展.合金热疲劳裂纹扩展具有一定的晶体学取向,沿{111}面〈110〉方向即与枝晶生长方向呈45°角扩展.
关键词:
DZ951合金
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热疲劳
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裂纹萌生和扩展
Journal of Materials Processing Technology
Influence of different heat treatments on microstructure and stress rupture property of DZ951 alloy was investigated. The results show that the shape of carbide changes from script-like of as-cast alloy to blocky during heat treatment, which can prevent microcrack initiation and propagation at or near carbides. The stress rupture life of DZ951 alloy at 1100 degrees C/60 Wa increases with the rise of solution temperature until 1240 degrees C then it begins to decrease. The size of cuboidal gamma' phase and the volume of spherical gamma' phase increase with the rise of aging temperature. Bimodal gamma' phase is achieved at higher aging temperature. Better stress rupture property for DZ951 alloy may be obtained by reasonable combination of the size and volume fraction of cuboidal and spherical gamma' phase. The fractographs of DZ951 alloy at different conditions show a ductile fracture mode. (c) 2007 Elsevier B.V. All fights reserved.
关键词:
DZ951 alloy;heat treatment;microstructure;stress rupture property;base superalloy;mechanical-properties;creep-properties;single-crystal;size
储昭贶
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于金江
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孙晓峰
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管恒荣
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胡壮麒
稀有金属材料与工程
研究了定向凝固镍基高温合金DZ951在广泛应力范围(50～970 MPa)内的高温(650～1040 ℃)持久性能.利用SEM观察了持久断裂的断口和变形后的组织结构.结果表明,DZ951合金的持久强度明显高于DZ40M合金,与DZ17G合金相当.温度低于800 ℃时,γ'相形貌基本不发生变化;温度达到900 ℃时,γ'相形成完整的筏型结构.低温(<760 ℃)下合金表现为解理断裂,中温(760～850 ℃)下为解理和准解理混合型断裂,碳化物成为有效的裂纹源.高温(>850 ℃)下合金的持久断裂转变为微孔聚集型断裂,显微疏松成为主要的裂纹源.
关键词:
定向凝固镍基高温合金
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持久性能
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组织
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断裂行为
Oxidation of Metals
The isothermal oxidation behavior at 1000, 1050 and 1100 degrees C and the cyclic oxidation behavior at 1000 degrees C of the directionally solidified Ni-base superalloy DS951 were investigated. The oxidized samples were characterized by SEM, EDAX, XRD. The alloy DS951 obeyed a two-stage parabolic rate law during isothermal oxidation at 1000-1100 degrees C. In cyclic conditions, the alloy showed no weight loss even after 1100 cycles. Cross-sectional examination revealed the development of faceted and needle-shaped AlN precipitates in the alloy subsurface region during cyclic oxidation, while no internal corrosion products were found in isothermal tests. Furthermore, a selective oxidation of MC carbides (M was predominately niobium with some chromium and tungsten) was observed along alloy grain boundaries and in interdendritic areas.
关键词:
Ni-base superalloy;DS951;oxidation;kinetics;microstructure;cr-al alloys;internal oxidation;high-temperature;theta-alpha-al2o3;transformation;nitridation;scales
Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science
The high-temperature creep deformation and fracture behavior of a directionally solidified Ni-base superalloy DZ951 have been investigated over a wide stress range of 110 to 880 MPa at high temperatures (700 degrees C to 1000 degrees C). In this article, the detailed creep deformation and fracture mechanism have been studied. The results show that the creep curves exhibit strong temperature dependence. From transmission election microscopy (TEM) observations, it is suggested that the deformation mechanism is temperature dependent and mainly consists of three dislocation-controlling mechanisms: stacking faults and dislocation-pair shearing, dislocation bowing, and dislocation climbing. It is found that the fracture mode of DZ951 alloy changes from cleavagelike fracture at low temperature to ductile fracture at high temperature. At 700 degrees C, the creep cracks mainly initiate at the surface and propagate along the cleavagelike facets. With increasing temperature, cracks can initiate at the surface, carbide/matrix interface, and cast pore. The growth of microcrack has a direction perpendicular to the stress direction. The creep-rupture data follow the Monkman-Grant relationship in different temperature regions.
关键词:
single-crystal superalloy;dislocation reactions;stress-rupture;crack-growth;nimonic 80a;mechanisms;grain;orientation;gtd-111;alloy
