The Al-Si alloy matrix composite reinforced by γ-Al2O3 particles was produced by adding NH4AlO(OH)HCO3(AACH) into molten Al-Si alloy at 850 ℃. During stirring γ-Al2O3 particles are formed by the decomposing reactio...The Al-Si alloy matrix composite reinforced by γ-Al2O3 particles was produced by adding NH4AlO(OH)HCO3(AACH) into molten Al-Si alloy at 850 ℃. During stirring γ-Al2O3 particles are formed by the decomposing reaction of AACH. It is found that the γ-Al2O3 particles distribute more uniformly in the matrix by adding AACH than by adding γ-Al2O3 directly. The wear tests show that the volume loss of the unreinforced Al-Si alloy matrix is about 3 times larger than that of the γ-Al2O3 reinforced composites and that of the composites fabricated by adding γ-Al2O3 is larger than that by adding AACH.展开更多
Effects of the volume fraction and the size of crystallized alumina silicate short fibers as well as heat treatment processes on micro-yield strength(MYS) of Al2O3-SiO2(sf)/Al-Si metal matrix composite(MMC) that was f...Effects of the volume fraction and the size of crystallized alumina silicate short fibers as well as heat treatment processes on micro-yield strength(MYS) of Al2O3-SiO2(sf)/Al-Si metal matrix composite(MMC) that was fabricated by squeezing cast, were investigated by using continuous loading method on an Instron 5569 tester with a special extensometer with an accuracy of 10?7. The results show that MYS of MMC decreases with the increase of volume fraction and length of the alumina silicate short fibers in the metal matrix composite, respectively. MYS of quenched Al2O3-SiO2(sf)/Al-Si MMC is the lowest, MYS of the MMC through peak-aging treatment is higher than that through other heat treatment methods. And before the peak-aging, MYS of MMC aging treated gradually increases with the increase of the aging time. Aging treatment after solution treatment is a preferred way that enhances micro and macro-yield strength of Al2O3-SiO2(sf)/Al-Si MMC.展开更多
A new steel matrix wear resistant composite reinforced by in situ granular eutectics can be obtained by modifying with a Si-Ce-Ti compound in the steel melt. The result indicates that the in situ granular eutectic is...A new steel matrix wear resistant composite reinforced by in situ granular eutectics can be obtained by modifying with a Si-Ce-Ti compound in the steel melt. The result indicates that the in situ granular eutectic is a pseudo-eutectic of austenite and (Fe,Mn)3C, which is formed between austenite dendrites during solidification due to the segregation of C and Mn impelled by modifying elements. The quantity of in situ granular eutectic reaches up to 8%-12% and its grain size is in the range from 10um to 20um. The austenite steel matrix wear resistant composite reinforced by in situ granular eutectic (abbreviated AGE composite) and austenite-bainite steel mains wear resistant composite reinforced by in situ granular eutectic (abbreviated ABGE composite) are obtained in the as-cast state and by air hardening, respectively. The wear resistance of the AGE and ABGE composites can be more greatly increased than that of their matrix steels under low and medium impact working condition.展开更多
The selection of milling tools for Si C14Cu4Mg0.5Si based on Aluminium matrix 2A14 was analyzed, and the factors that affect the efficiency of the milling were discussed. The Si C14Cu4Mg0.5Si was designed for use on t...The selection of milling tools for Si C14Cu4Mg0.5Si based on Aluminium matrix 2A14 was analyzed, and the factors that affect the efficiency of the milling were discussed. The Si C14Cu4Mg0.5Si was designed for use on the moon landing vehicle or missile wings, but the hardness of aluminium-silicon carbide composite material was very high, much higher than the general hardness of cemented carbide, which will bring many difficulties in the aluminium-silicon carbide composite material processing. The chemical compositions of Si C14Cu4Mg0.5Si were analyzed. A new selected indexable cutter was designed to mill Si C14Cu4Mg0.5Si. The structure design of milling cutter was different from the conventional milling cutter, breaking the previous limitations to a certain extent, pioneering the idea. The tool material wear was detected by experiments. The mechanical and physical properties of Si C14Cu4Mg0.5Si were also tested. Si C14Cu4Mg0.5Si exhibited different surface quality characteristics under different milling tools.展开更多
Al-Si metal matrix composites (MMCs) reinforced with 20 vol.% alumina-silicate shot fibers (Al2O3-SiO2(sf)) were fabricated by an infiltration squeeze method. Pure Pr metal was added into these composites. The effect ...Al-Si metal matrix composites (MMCs) reinforced with 20 vol.% alumina-silicate shot fibers (Al2O3-SiO2(sf)) were fabricated by an infiltration squeeze method. Pure Pr metal was added into these composites. The effect of Pr addition on the microstructure evolution of Al-Si MMCs was investigated by SEM,TEM,and EDS. Pr addition is favorable to make uniform microstructures with the modified eutectic Si crystal. PrAlSi phase with high contents of Pr and Si is observed on the interface between the fiber and the m...展开更多
Ni34.1 Fe27.9B18 Si18 Nb2 coating was deposited on mild steel substrate using high power laser cladding followed by laser remelting process. The laser processing was conducted by the powder feeding method using low pu...Ni34.1 Fe27.9B18 Si18 Nb2 coating was deposited on mild steel substrate using high power laser cladding followed by laser remelting process. The laser processing was conducted by the powder feeding method using low purity materials without shielding box. To learn the surface amorphous matrix coating forming mechanism, the coating without remelting process was also studied. The phases and microstructures were analyzed by X-ray diffraction （XRD）, scanning- and transmission-electron microscopy（ SEM, TEM）. The microhardness and corrosion resistance property of the coating were also measured. The results of SEM, XRD and TEM analysis show that the remelted coating has an amorphous matrix layer embedded with some crystals due to high cooling rate during remelting process. The crystals phases are identified as Fe2 B phase, γ （Fe, Ni ） phase and α- Fe phase. No oxidation phases are found in the coating surface. Hardness profiles reveal microhardness more than 1 100 HVo.5 over the full depth of the amorphous matrix layer, while the unremtled coating and the substrate show relatively lower hardness than the remelted layer. Corrosion resistance tests exhibit that the remelted coating is nobler than the unremelted coating and the substrate material.展开更多
基金Project(105055) supported by Key Project of Ministry of Education of China
文摘The Al-Si alloy matrix composite reinforced by γ-Al2O3 particles was produced by adding NH4AlO(OH)HCO3(AACH) into molten Al-Si alloy at 850 ℃. During stirring γ-Al2O3 particles are formed by the decomposing reaction of AACH. It is found that the γ-Al2O3 particles distribute more uniformly in the matrix by adding AACH than by adding γ-Al2O3 directly. The wear tests show that the volume loss of the unreinforced Al-Si alloy matrix is about 3 times larger than that of the γ-Al2O3 reinforced composites and that of the composites fabricated by adding γ-Al2O3 is larger than that by adding AACH.
基金Project(19972021)supported by the National Natural Science Foundation of China
文摘Effects of the volume fraction and the size of crystallized alumina silicate short fibers as well as heat treatment processes on micro-yield strength(MYS) of Al2O3-SiO2(sf)/Al-Si metal matrix composite(MMC) that was fabricated by squeezing cast, were investigated by using continuous loading method on an Instron 5569 tester with a special extensometer with an accuracy of 10?7. The results show that MYS of MMC decreases with the increase of volume fraction and length of the alumina silicate short fibers in the metal matrix composite, respectively. MYS of quenched Al2O3-SiO2(sf)/Al-Si MMC is the lowest, MYS of the MMC through peak-aging treatment is higher than that through other heat treatment methods. And before the peak-aging, MYS of MMC aging treated gradually increases with the increase of the aging time. Aging treatment after solution treatment is a preferred way that enhances micro and macro-yield strength of Al2O3-SiO2(sf)/Al-Si MMC.
基金Acknowledgements - This project was supported by the National Natural Science Foundation of China (Grant No.50001008).
文摘A new steel matrix wear resistant composite reinforced by in situ granular eutectics can be obtained by modifying with a Si-Ce-Ti compound in the steel melt. The result indicates that the in situ granular eutectic is a pseudo-eutectic of austenite and (Fe,Mn)3C, which is formed between austenite dendrites during solidification due to the segregation of C and Mn impelled by modifying elements. The quantity of in situ granular eutectic reaches up to 8%-12% and its grain size is in the range from 10um to 20um. The austenite steel matrix wear resistant composite reinforced by in situ granular eutectic (abbreviated AGE composite) and austenite-bainite steel mains wear resistant composite reinforced by in situ granular eutectic (abbreviated ABGE composite) are obtained in the as-cast state and by air hardening, respectively. The wear resistance of the AGE and ABGE composites can be more greatly increased than that of their matrix steels under low and medium impact working condition.
基金Funded by the National Natural Science Foundation of China(Nos.51275490,and 51475346)Specialized Research Fund for the Doctoral Program of Higher Education of China(20131420120002)Shanxi Province Science Foundation(2013011025-1)
文摘The selection of milling tools for Si C14Cu4Mg0.5Si based on Aluminium matrix 2A14 was analyzed, and the factors that affect the efficiency of the milling were discussed. The Si C14Cu4Mg0.5Si was designed for use on the moon landing vehicle or missile wings, but the hardness of aluminium-silicon carbide composite material was very high, much higher than the general hardness of cemented carbide, which will bring many difficulties in the aluminium-silicon carbide composite material processing. The chemical compositions of Si C14Cu4Mg0.5Si were analyzed. A new selected indexable cutter was designed to mill Si C14Cu4Mg0.5Si. The structure design of milling cutter was different from the conventional milling cutter, breaking the previous limitations to a certain extent, pioneering the idea. The tool material wear was detected by experiments. The mechanical and physical properties of Si C14Cu4Mg0.5Si were also tested. Si C14Cu4Mg0.5Si exhibited different surface quality characteristics under different milling tools.
文摘Al-Si metal matrix composites (MMCs) reinforced with 20 vol.% alumina-silicate shot fibers (Al2O3-SiO2(sf)) were fabricated by an infiltration squeeze method. Pure Pr metal was added into these composites. The effect of Pr addition on the microstructure evolution of Al-Si MMCs was investigated by SEM,TEM,and EDS. Pr addition is favorable to make uniform microstructures with the modified eutectic Si crystal. PrAlSi phase with high contents of Pr and Si is observed on the interface between the fiber and the m...
基金Acknowledgements The authors would like to thank the financial support provided by the National Natural Science Foundation of China （No. 50971091 ）, the Ministry of the Science and Technology of the People＇s Republic of China （No. 2009DFB50350） , the Science and Technology Commission of Shanghai Municipality （ No. 08520704900） and the Economy and Information Commission of Shanghai Municipality （ No. zx08089）.
文摘Ni34.1 Fe27.9B18 Si18 Nb2 coating was deposited on mild steel substrate using high power laser cladding followed by laser remelting process. The laser processing was conducted by the powder feeding method using low purity materials without shielding box. To learn the surface amorphous matrix coating forming mechanism, the coating without remelting process was also studied. The phases and microstructures were analyzed by X-ray diffraction （XRD）, scanning- and transmission-electron microscopy（ SEM, TEM）. The microhardness and corrosion resistance property of the coating were also measured. The results of SEM, XRD and TEM analysis show that the remelted coating has an amorphous matrix layer embedded with some crystals due to high cooling rate during remelting process. The crystals phases are identified as Fe2 B phase, γ （Fe, Ni ） phase and α- Fe phase. No oxidation phases are found in the coating surface. Hardness profiles reveal microhardness more than 1 100 HVo.5 over the full depth of the amorphous matrix layer, while the unremtled coating and the substrate show relatively lower hardness than the remelted layer. Corrosion resistance tests exhibit that the remelted coating is nobler than the unremelted coating and the substrate material.
