材料期刊网

Phase Transformation and Its Effect on Mechanical Properties of C300 Weld Metal after Aging Treatment at Different Temperatures

Shuai YANG , Yun PENG , Xiao-mu ZHANG , Zhi-ling TIAN

钢铁研究学报

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Microstructure and Mechanical Properties of GMAW Weld Metal of 890 MPa Class Steel

Yun PENG , Xing-na PENG , Xiao-mu ZHANG , Zhi-ling TIAN , Tao WANG

钢铁

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Jian ZHANG/Langhong Lou

材料科学技术（英文）

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Effect of stress on mu phase formation in single crystal superalloys

Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing

Precipitation behavior of the mu phase under applied stress was systematically investigated in two single crystal superalloys CMSX-4 and R0. The investigation has shown that both the sign and magnitude of the applied stress can affect the precipitation behavior of the mu phase with a certain degree of regularity. At first, the precipitation of the mu phase varied significantly when a small amount of stress was applied, regardless of whether the specimen is under tension or under compression. Under most conditions however, precipitation of the mu phase was restrained by this low application of stress. After increasing the applied stress, precipitation of the mu phase increased relative to the amount of tension or decreased under compression. (C) 2010 Elsevier B.V. All rights reserved.

关键词: Single crystal superalloy;Topologically close-packed (TCP) phase;Thermal exposure;Rhenium (Re);kinetics;cmsx-4

A mu-Phase behavior in a cast Ni-base superalloy

Journal of Materials Science

The response of mu phase to applied stress and long-term thermal exposure has been investigated in the cast Ni-base superalloy K446. It is found that during stress rupture, the applied stress accelerates the precipitation and growth of mu phase. However, during thermal exposure the mu phase precipitating in the form of needles and granules experiences a complicated evolution. The needles, fiber- or sheet-shaped in three-dimension, align very regularly during exposure, either lying in three directions with an acute angle to one another or in two directions perpendicular to each other, the mechanisms of which are characterized in detail. In addition, it is concluded that an excessive precipitation of mu phase severely degrades the mechanical properties of the alloy, whereas its evolution behavior during thermal exposure is determined to have an insignificant influence on the properties.

关键词: single-crystal superalloy;thermal exposure;precipitation;stability;rupture;stress

Precipitation behavior of mu phase and creep rupture in single crystal superalloy CMSX-4

Journal of Alloys and Compounds

Precipitation behavior of a topologically close packed (TCP) mu phase as well as its role during the creep deformation in single crystal superalloy CMSX-4 have been investigated. The mu particles nucleated and grew based on low index planes of both the mu phase ({11 (2) over bar 0} and {1 0 (1) over bar0}) and the matrix ({110}, {001} or {111} and {112}) by epitaxial growth toward < 0001 >(mu) or < 110 >gamma directions, which predominantly resulted in a rod-like morphology. Interestingly, composition of these rod-like mu particles varied with the ratio of Ni/(W + Re) due to the different diffusion rates of these elements in the matrix during thermal exposure. Moreover, the gamma' evolution played an important role in the precipitation behavior and the fracture behavior of the mu phase. The rod-like mu particles were not fractured by stress concentration, as they were surrounded by the gamma' envelope. (C) 2011 Elsevier B.V. All rights reserved.

关键词: Nickel-base single crystal superalloy;Topologically close packed phase;Thermal exposure;Creep;nickel-base superalloys;ni;deformation;microstructure;mechanisms;diffusion;exposure;fatigue;design;damage

Intergrowth of P phase with mu phase in a Ru-containing single-crystal Ni-based superalloy

Philosophical Magazine Letters

The precipitation of topologically close-packed (TCP) phases in a Ru-containing single-crystal Ni-based superalloy has been investigated. The high-angle annular dark field, selected area electron diffraction, and high-resolution transmission electron microscopy were used to analyze the TCP precipitates in this study. The intergrowth of P phase with m phase was found. This finding indicates that P phase may nucleate at stacking faults and subsequently grow at the expense of mu phase. The orientation relationship between P and mu phases was (1 0 0)(P)//(1 (1) over bar 1 2)(mu) and [0 1 (1) over bar](P)/[4 2 (1) over bar](mu).

关键词: superalloys;topologically close-packed phases;intergrowth;scanning;transmission electron microscopy;electron-microscopy;packed phases;precipitation;behavior;microstructure;deformation;co7w6

On the role of mu phase during high temperature creep of a second generation directionally solidified superalloy

Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing

The role of mu phase in a second generation directionally solidified Ni-base superalloy during high temperature creep has been characterized in the present work. A large amount of blocky mu phase enveloped by thick gamma'-film is found at the grain boundaries and in the vicinity of primary MC carbides after heat treatment. However, the creep-rupture properties of the alloy are not affected by the presence of the blocky p, phase at 760-1070 degrees C under a stress of 120-850 MPa. By the investigation of creep microstructure at 975 degrees C/255 MPa, it is found that the thick gamma'-film plays a pivotal role in toughening the grain boundaries and the interfaces between the mu phase (or carbides) particles and the matrix, and preventing the formation of cracks. Meanwhile, during high temperature creep, M(23)C(6) carbides are continuously coarsening with the dissolution of the p. phase particles and MC carbides, especially at the grain boundaries. The poor interface cohesion strength between such large M(23)C(6) carbides and the gamma matrix at the vertical segments of the directionally solidified grain boundaries leads to the final creep failure of the present alloy. (C) 2010 Elsevier B.V. All rights reserved.

关键词: mu phase;Directionally solidified Ni-base superalloy;Creep;Carbide;Grain boundaries;precipitation

Lateral photovoltage of B-doped ZnO thin films induced by 10.6 mu m CO(2) laser

Journal of Physics D-Applied Physics

B-doped ZnO thin films were observed to have a lateral laser-induced photovoltaic effect: the saturation value varied very linearly with the 10.6 mu m constant laser spot position between the electrodes on the ZnO surface. It was found that the temperature gradient in the direction of electron transfer (along the film surface) due to the laser spot causes this photovoltage signal to be linearly dependent on the position of the laser spot in this isotropic system. This linearity is expected to make ZnO a candidate for position-sensitive photodetectors.

关键词: ultraviolet photodetectors

MU5.0再生骨料混凝土空心砌块配合比设计

卓玲 , 陈宝璠

硅酸盐通报

利用废弃混凝土加工成的再生骨料制作再生混凝土空心砌块.在混凝土空心砌块配合比参数优化设计的基础上,以再生骨料混凝土空心砌块抗压强度作为评定指标,采用正交试验方法,研究再生骨料混凝土空心砌块配合比设计.研究结果表明:对于再生骨料混凝土空心砌块,以85％再生粗骨料取代率和100％再生细骨料取代率,选取合适配合比,其强度等级是可以达到MU5.0的.

关键词: 再生骨料混凝土空心砌块 , 再生粗骨料取代率 , 配合比 , 设计