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Microstructure and texture evolution in commercial-purity Zr 702 during cold rolling and annealing

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International Journal of Minerals,Metallurgy and Materials 2014年第8期21卷 785-795页

作者： Min Ma Ming-he Li Yuan-biao Tan Hui Yuan Wen-chang Liu Key Laboratory of Metastable Materials Science and Technology College of Materials Science and Engineering Yanshan University

Microstructure and texture evolution in commercial-purity Zr 702 during cold rolling and annealing was investigated by optical microscopy, transmission electron microscopy, and X-ray diffraction. The results showed that crystallographic slip was the predominant deformation mechanism in the early stage of deformation. Deformation twins started to form when the rolling reduction was larger than 38.9%; both the dislocation density and the number of twins increased with increasing rolling reduction. The initial texture of the Zr 702 plate consisted of the basal fiber component. During cold rolling the strength of the basal fiber first decreased and then increased with increasing rolling reduction. The cold-rolled sheets were fully recrystallized after being annealed at 550℃. The recrystallization temperature and the size of recrystallized grains decreased with increasing rolling reduction. A larger rolling reduction resulted in a higher grain growth rate when the annealing temperature increased from 550℃ to 700℃. The recrystallization texture was characterized by a major basal fiber and a minor {0113}〈2110〉 component. The strength of the recrystallization texture increased with increasing rolling reduction.

关键词： zirconium cold rolling annealing microstrucmre texture recrystallization

Hot deformation behavior of uniform fine-grained GH4720Li alloy based on its processing map

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International Journal of Minerals,Metallurgy and Materials 2016年第1期23卷 83-91页

作者： Qiu-ying Yu Zhi-hao Yao Jian-xin Dong Beijing Institute of Aeronautical Materials Beijing 100095 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

The hot deformation behavior of uniform fine-grained GH4720Li alloy was studied in the temperature range from 1040 to 1130℃ and the strain-rate range from 0.005 to 0.5 s-1 using hot compression testing. Processing maps were constructed on the basis of compression data and a dynamic materials model. Considerable flow softening associated with superplasticity was observed at strain rates of 0.01 s 1 or lower. According to the processing map and observations of the microstructure, the uniform fine-grained microstructure remains intact at 1100℃ or lower because of easily activated dynamic recrystallization （DRX）, whereas obvious grain growth is observed at 1130℃. Metal- lurgical instabilities in the form of non-uniform microstrucmres under higher and lower Zener-Hollomon parameters are induced by local plastic flow and primary γ＇ local faster dissolution, respectively. The optimum processing conditions at all of the investigated strains are pro- posed as 1090-1130℃ with 0.084）.5 s-1 and 0.0054）.008 s-1 and 1040-1085℃ with 0.0054）.06 s-1.

关键词： superalloys hot deformation processing maps microstrucmre superplasticity

Facile Synthesis of Nanocrystalline Cr_2O_3 Thin Film

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Journal of Wuhan University of Technology(Materials Science) 2011年第6期26卷 1032-1035页

作者：杨明 School of Transportation Southeast University

A novel and facile synthesis route for the manufacture of transparent and uniform self-assembled nanocrystalline Cr2O3 （nc-Cr2O3） thin films with different morphology was reported, utilizing chromium nitrate as the inorganic source and triblock copolymer F127 as the morphology-directing agent by the evaporation-induced assembly （EIA） method. X-ray powder diffraction （XRD）, thermogravimetry-differential scanning calorimetry （TG-DSC）, N2-sorption, scanning electron microscopy （SEM） and transmission electron microscopy （TEM） were used to characterize the as-prepared nc-Cr2O3 thin films. The Cr2O3 thin film with different morphology was obtained by changing the relative humidity. The possible formation mechanism of the nc-Cr2O3 thin films with different morphologies was discussed.

关键词： microstrucmre Cr2O3 thin film

Effect of indium addition on the microstructural formation and soldered interfaces of Sn-2.5Bi-1Zn-0.3Ag lead-free solder

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International Journal of Minerals,Metallurgy and Materials 2012年第11期19卷 1029-1035页

作者： Ming-jie Dong Zhi-ming Gao Yong-chang Liu Xun Wang Li-ming Yu School of Materials Science&Engineering Tianjin Key Laboratory of Advanced Jointing TechnologyTianjin UniversityTianjin 300072China

The microstructural formation and properties of Sn-2.5Bi-xln-lZn-0.3Ag （in wt%） alloys and the evolution of soldered interfaces on a Cu substrate were investigated. Apart from the relatively low melting point （about 195C）, which is close to that of conventional eutectic Sn-Pb solder, the investigated solder presents superior wettability, solderability, and ductility. The refined equiaxial grains enhance the me- chanical properties, and the embedded bulk intermetallic compounds （IMCs）（Cu6Sn5 and CusZns） and granular Bi particles improve the joint reliability. The addition of In reduces the solubility of Zn in the 13-Sn matrix and strongly influences the separation and growth behaviors of the IMCs. The soldered interface of Sn-2.5Bi-xln-lZn-0.3Ag/Cu consists of Cu-Zn and Cu-Sn IMC layers.

关键词： soldering alloys indium microstrucmre interfaces melting point intermetallics