Na WANG
,
Chungen ZHOU
,
Shengkai GONG
材料科学技术（英）
The nanostructured zirconia coatings were deposited by atmospherically plasma spraying. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction were used to investigate the microstructure of the zirconia coatings. Thermal diffusivity values at normal temperatures have been evaluated by laser flash technique. Effect of annealing on the microstructure evolution of the zirconia coating has been performed. The grains and thermal diffusivity are increased with increasing annealing time and temperature. The grain growth is according to the GRIGC (the grain rotation induced grain coalescence) mechanism. The increase in thermal diffusivity is attributed to the grain growth and the decrease in porosity of nanostructured zirconia coatings.
关键词:
Grain size
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null
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null
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Leng CHEN
,
Weimin MAO
,
Yongning YU
,
Huiping FENG
材料科学技术（英）
An X-ray diffractometer that equipped with a two-dimensional detector is used for developing the technique of grain size measurement for strong textured and coarse-grained Si steel sheet. The method is based on the concept that the position of diffraction spots depends on the orientation of individual grains. The two-dimensional detector has the ability to collect abundant diffraction information in seconds, thus it can be determined rapidly and accurately whether a series of diffraction spots come from the same grain. The experimental results show that this method can be used for measuring grain size and its distribution in strong textured and coarse-grained metal sheets.
关键词:
Grain size
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null
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He YANG
,
Yuli LIU
,
Wang CAI
,
Mei ZHAN
材料科学技术（英）
Blade precision forging is a high temperature and large plastic deformation process. Interact of deformation and heat conduction results in producing large temperature unevenness inside the billet. The unevenness has a great effect on the mechanical property and microstructure of the forged blade. However, internal quality of the blade is decided by its microstructure, it is necessary to conduct a research on the microstructure of the blade forging process. Taking a blade with a tenon as an object, its precision forging process is simulated and analyzed using a 3D coupled thermo-mechanical FEM code. And based on the prediction model of Ti-6Al-4V presented by the predecessor, a study of the evolution of grain size in the forging process is made. The distribution characteristics of grain size in typical sections are obtained under various deformation degrees. This study may provide a base for designing the blade forging process and working out its parameters.
关键词:
Blade
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null
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null
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Miaoquan LI
,
Shankun XUE
,
Aiming XIONG
,
Shenghui CHEN
材料科学技术（英）
Hot compression was conducted at a Thermecmaster-Z simulator, at deformation temperatures of 800~1040℃, with strain rates of 0.001~50 s-1 and height reduction of 50%. Grain size of the prior α phase was measured with a Leica LABOR-LUX12MFS/ST microscope to which QUANTIMET 500 software for image analysis for quantitative metallography was linked. According to the present experimental data, a constitutive relationship for a TC6 alloy and a model for grain size of the prior α phase were established based on the Arrhenius' equation and the Yada's equation, respectively. By finite element (FE) simulation, deformation distribution was determined for isothermal forging of a TC6 aerofoil blade at temperatures of 860~940℃ and hammer velocities of 9~3000.0 mm/min. Meanwhile, the grain size of the prior α phase is simulated during isothermal forging of the TC6 aerofoil blade, by combining FE outputs with the present grain size model. The present results illustrate the grain size and its distribution in the prior α phase during the isothermal forging of the TC6 aerofoil blade. The simulated results show that the height reduction, deformation temperature, and hammer velocity have significant effects on distribution of the equivalent strain and the grain size of the prior α phase.
关键词:
Titanium alloy
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null
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null
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null
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Chunyan BAN
,
Wenqing GAO
,
Guiyi ZENG
,
Qixian BA
,
Hualin ZENG
材料科学技术（英）
The magnetic properties of Fe72.5Cu1Nb2V2Si13.5B9 alloy are investigated from an amorphous to a nanocrystalline and complete crystalline state. The sample annealed at 550℃ for 0.5 h shows a homogeneous nanocrystalline structure and presents excellent soft magnetic properties. When the specimens were annealed at a temperature above 600℃, the magnetic properties are obviously deteriorated because the grain size grows up, exceeding the exchange length.
关键词:
Fe72.5Cu1Nb2V2Si13.5B9 alloy
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null
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