The modification of silicon in an Al-30Si alloy was studied using optical microscopy, electron probe micro-analysis, transmission electron microscopy and differential scanning calorimetry. It is found that phosphorus ...
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The modification of silicon in an Al-30Si alloy was studied using optical microscopy, electron probe micro-analysis, transmission electron microscopy and differential scanning calorimetry. It is found that phosphorus master alloys combined with boron master alloys have good modification effect on primary silicon but no evident modification effect on eutectic silicon, while boron combined with cerium has good modification effect on eutectic silicon. The results of differential scanning calorimetry show that phosphorus, boron or cerium addition and their combined addition have different undercooling effects on eutectic silicon. Many scholars thought that AlP particles were the nuclei of eutectic silicon when phosphorus was enough in the alloy. Our results show that β-（Al,Si,Fe） can still be the nucleus of plate-like entectic silicon while AlP is the nucleus of primary silicon when there is enough phosphorus in the melt. In addition, the mechanism about the modification was also discussed.
The composite coating of CNTs/HAp has been prepared on a titanium substrate by the method of electrophoretic deposition technique. The results of XRD indicated that after sintering at 800°C for 2h in argon the ma...
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The composite coating of CNTs/HAp has been prepared on a titanium substrate by the method of electrophoretic deposition technique. The results of XRD indicated that after sintering at 800°C for 2h in argon the main component of the composite coating is hydroxyapatite and carbon nano-tube. Micrograph of composite coating expressed that the composite coating is symmetrical and compact. CNTs was dispered in hydroxyapatite particles symmetrical and CNTs was coated uniformity by hydroxyapatite. With the content of carbon nanotube increased from 20 percent to 50 percent the density of the composite coating increased gradually and the surface quality improved gradually.
The liquid structure of Co79.5Sn20.5 eutectic alloy has been investigated by means of X-ray diffraction. The result shows that the liquid structure of Co79.5Sn20.5 alloy displays quite stable from 1350℃ to 1150℃ alt...
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The liquid structure of Co79.5Sn20.5 eutectic alloy has been investigated by means of X-ray diffraction. The result shows that the liquid structure of Co79.5Sn20.5 alloy displays quite stable from 1350℃ to 1150℃ although the short-range order increases with temperature *** addition,the correlation between the liquid structure and solid structure also has been analyzed by"the nanocrystal model".It is shown that the melt of Co79.5Sn20.5 alloy consists ofβCo3Sn2 clusters andβCo clusters, indicating that the liquid structure and solid structure of Co79.5Sn20.5 eutectic alloy are strikingly similar.
The effects of solution treatment and aging process on microstructure and mechanical properties of powder hot extruded Al-Zn-Mg-Cu alloy were investigated by X-ray diffractometer, optical and transmission electron mic...
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The effects of solution treatment and aging process on microstructure and mechanical properties of powder hot extruded Al-Zn-Mg-Cu alloy were investigated by X-ray diffractometer, optical and transmission electron microscope, microhardness and tensile tests. The result shows that a large number of MgZn2 particles were precipitated from Al matrix during extrusion. The optimal T6 treatment process of the alloy is 460°C×2.5h+120°C×24h. Tensile strength, yield strength and elongation of the T6 treated alloy are 731MPa, 670MPa and 6.2%, respectively. The reason that the microstructure of T6 treated alloy is similar to that of cast and then extruded Al-Zn-Mg-Cu alloy after retrogression and reaging (RRA) is mainly attributed to grain refinement.
Microstructure of novel austenitic heat-resistance steel Super304H after aging at different temperatures was investigated by means of scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diff...
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Microstructure of novel austenitic heat-resistance steel Super304H after aging at different temperatures was investigated by means of scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The experimental results indicate that the precipitated phases of Nb(C, N), Cu-rich phase, M23C6 and NbCrN are detected depending on different aging temperatures, when the super304H steel is aged at 700~1250°C. With the variation of aging temperature, the different precipitated phases were observed in the steel, and the morphology and amount of the precipitates changed. M23C6 carbides mainly precipitated along grain boundary for the steel aged at 700~900°C, leading to deteriorate high temperature creep strength and intergranular corrosion resistant of Super304H steel.
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