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Effect of melt superheating treatment on crystallization behavior and magnetic properties of melt-spun Fe-rich Nd-Fe-B ribbons
作者: 盛洪超, 曾燮榕, 胡强, 邓飞 主题: microstructure, nanocomposite magnets, melt superheating treatment, rare earths 年份: 2010
摘要: melt-spun nd7fe90b3 ribbons were prepared under different melt treatment conditions,i.e.,the melt temperature was varied prior to ejection onto the quenching wheel.the microstructure characteristics,crystallization behavior,and subsequent magnetic properties of α-fe/nd2fe14b-based exchange-spring magnets were investigated using x-ray diffraction,differential scanning calorimeter,transmission electron microscopy,and vibrating sample magnetometer.it was shown that melt spinning at different quenching temperatures caused the as-quenched ribbons to have distinctive crystallization behavior.under high quenching temperature,precipitation of tbcu7 type phase was inhibited during crystallization,resulting in remarkable reduction of grain size.this led to strengthening of exchange coupling effect between the magnetically hard and soft phase and improvement of magnetic properties of annealed ribbons.
Effect of super heat treatment on crystallization behavior and magnetic properties of Nd_(4.5)Fe_(77)B_(18.5) nanocomposites
作者: 盛洪超, 曾燮榕, 邹继兆, 谢盛辉 主题: nanocomposite magnets, amorphous alloys, superheat treatment, rare earths 年份: 2010
摘要: melt-spun nd4.5fe77b18.5 ribbons were prepared under various superheat temperatures.the microstructure characteristics,crystallization behavior,and subsequent magnetic properties of fe3b/nd2fe14b nanocomposite magnets were investigated using x-ray diffraction,differential thermal analysis,and vibrating sample magnetometry.it was shown that melt spinning at different quenching temperatures caused the as-quenched ribbons to have distinctive crystallization behavior.depending on superheat temperature,phase transformation of the ribbons during annealing may take place in one of the following sequences:(1) amorphous phase(am)→am'+fe3b→fe3b+ nd2fe23b3→ fe3b+nd2fe14b,or(2) amorphous phase(am)→am'+fe3b→fe3b+nd2fe14b.for the latter,the ribbon after optimal annealing exhibited single-phase magnetic behavior.in the first case,magnetic properties of the optimally heat treated ribbons deteriorated and an apparent kink could be seen along the demagnetization curves near the zero field.
Effect of Chloride Content on Bond Behavior Between FRP and Concrete
作者: 潘金龙, 黄毅方, 邢锋 主题: fiber reinforced polymer (FRP), concrete, chloride content, direct shear test, debonding behavior 年份: 2010
摘要: for reinforced concrete structures located along the seaside, the penetration of chloride ions into concrete may be a threat to the durability of the structures. experimental investigations were carried out to study the effect of chloride content on the bond behavior between concrete and fiber reinforced polymer (frp) plates. direct shear tests were conducted on the frp strengthened concrete members. before testing, the specimens were immersed in nacl solutions with concentrations ranging from 3%—15% for different time (0—120 d). then, the specimens were dried and tested to obtain the initial and ultimate debonding loads, together with strain distributions along the frp plates of different load values. the correlations between chloride content and debonding parameters are established. test results show that the debonding parameters are closely related to the immersing time rather than the chloride content of the solution.
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