A hypereutectic Al-50 wt%Si alloy for electronic packaging was prepared by spark plasma sintering(SPS)technology using gas-atomized Al-50 wt%Si powder.The effect of sintering parameters on alloy phase composition,micr...A hypereutectic Al-50 wt%Si alloy for electronic packaging was prepared by spark plasma sintering(SPS)technology using gas-atomized Al-50 wt%Si powder.The effect of sintering parameters on alloy phase composition,microstructure,thermal performance and the tensile strength at different temperatures was investigated.The experimental results show that the alloy can obey the diffraction peaks of silicon and aluminum without other peaks appearing.The primary silicon in the prepared alloy can be evenly distributed in the aluminum matrix.The coefficient of thermal expansion(CTE)and thermal conductivity(TC)of the alloy will improve with the increase of sintering temperature,but they will decrease after sintering for a long time,which is caused by the large difference of coefficient of thermal expansion between silicon and aluminum.The tensile properties of the alloy at room temperature will increase with the increase of sintering temperature,but higher test temperatures will inhibit the tensile properties except the elongation.The morphology and fracture mode of the tensile fracture are also analyzed to determine the good bonding strength of the alloy.展开更多
Three groups of AlSiTiCrNiCu high entropy alloy(HEA)particles reinforced Al606l composites were fabricated by spark plasma sintering at 520 and 570℃(S520,S570)and by hot-pressed sintering at 570℃(H570).The AlSiTiCrN...Three groups of AlSiTiCrNiCu high entropy alloy(HEA)particles reinforced Al606l composites were fabricated by spark plasma sintering at 520 and 570℃(S520,S570)and by hot-pressed sintering at 570℃(H570).The AlSiTiCrNiCu(AST)particles used as reinforcements were synthesized by mechanical alloying.The influences of the sintering process on the microstructure and mechanical properties of composites were investigated.The results showed that the AST particles had a near-equiatomic composition with a single BCC structure.The sintering temperature and time had a coupling influence on the interfacial microstructure.S520 had hardly reaction products and slight interfacial diffusion,and the AST particles were completely high entropy.Intense interfacial reactions happened on S570 and H570 with the same reaction products.The element diffusion of S570 was focused on the edge of the AST particles with partial loss of high entropy.Complete element diffusion and entire loss of high entropy of AST particles happened on H570.The differences in the microstructure caused by the three preparation methods led to the changes in mechanical properties and fracture mechanisms of composites.展开更多
Al-doped ZnO(AZO) is considered as an alternative to transparent conductive oxide materials.Patterning and achieving a stable surface are important challenges in the development and optimization of dry etching process...Al-doped ZnO(AZO) is considered as an alternative to transparent conductive oxide materials.Patterning and achieving a stable surface are important challenges in the development and optimization of dry etching processes, which must be overcome for the application of AZO in various devices. Therefore, in this study, the etch rate and surface properties of an AZO thin film after plasma etching using the adaptive coupled plasma system were investigated. The fastest etch rate was achieved with a CF_(4)/Ar ratio of 50:50 sccm. Regardless of the ratio of CF_(4) to Ar,the transmittance of the film in the visible region exceeded 80%. X-ray photoelectron spectroscopy analysis of the AZO thin film confirmed that metal-F bonding persists on the surface after plasma etching. It was also shown that F eliminates O vacancies. Consequently, the work function and bandgap energy increased as the ratio of CF-4 increased. This study not only provides information on the effect of plasma on AZO thin film, but identifies the cause of changes in the device characteristics during device fabrication.展开更多
Hypereutectic Al-40 wt.%Si alloys were fabricated by the combination of gas atomization and spark plasma sintering(SPS) technology. The effects of holding time(15-60 min) on phase composition, microstructure, density,...Hypereutectic Al-40 wt.%Si alloys were fabricated by the combination of gas atomization and spark plasma sintering(SPS) technology. The effects of holding time(15-60 min) on phase composition, microstructure, density,mechanical properties of Al-Si alloys were investigated by XRD, SEM, a hydrostatic balance, an automatic micro hardness tester and a universal tensile testing machine. The results showed that homogenous distribution of ultrafine primary Si and high density of alloys can be obtained at holding time of 30 min. Compared with primary Si(3.7 μm)fabricated by gas atomization, the average size increased from 5.17 to 7.72 μm with the increase of holding time during SPS process. Overall, the relative density, maximum tensile strength and Vickers hardness of 94.9%, 205 MPa and HV;196.86 were achieved at holding time of 30 min, respectively. In addition, all the diffraction peaks were corresponded to α-Al or β-Si and no other phase can be detected. Finally, the densification process of SPS was also discussed.展开更多
基金the Shanxi Key Laboratory of Nano-materials and Technology,China(Nos.18JS060,17JS075)。
文摘A hypereutectic Al-50 wt%Si alloy for electronic packaging was prepared by spark plasma sintering(SPS)technology using gas-atomized Al-50 wt%Si powder.The effect of sintering parameters on alloy phase composition,microstructure,thermal performance and the tensile strength at different temperatures was investigated.The experimental results show that the alloy can obey the diffraction peaks of silicon and aluminum without other peaks appearing.The primary silicon in the prepared alloy can be evenly distributed in the aluminum matrix.The coefficient of thermal expansion(CTE)and thermal conductivity(TC)of the alloy will improve with the increase of sintering temperature,but they will decrease after sintering for a long time,which is caused by the large difference of coefficient of thermal expansion between silicon and aluminum.The tensile properties of the alloy at room temperature will increase with the increase of sintering temperature,but higher test temperatures will inhibit the tensile properties except the elongation.The morphology and fracture mode of the tensile fracture are also analyzed to determine the good bonding strength of the alloy.
基金Funded by the National Natural Science Foundation of China(Nos.52071117,51771063)the Heilongjiang Provincial Science Fund for Distinguished Young Scholars(No.JQ2021E002)
文摘Three groups of AlSiTiCrNiCu high entropy alloy(HEA)particles reinforced Al606l composites were fabricated by spark plasma sintering at 520 and 570℃(S520,S570)and by hot-pressed sintering at 570℃(H570).The AlSiTiCrNiCu(AST)particles used as reinforcements were synthesized by mechanical alloying.The influences of the sintering process on the microstructure and mechanical properties of composites were investigated.The results showed that the AST particles had a near-equiatomic composition with a single BCC structure.The sintering temperature and time had a coupling influence on the interfacial microstructure.S520 had hardly reaction products and slight interfacial diffusion,and the AST particles were completely high entropy.Intense interfacial reactions happened on S570 and H570 with the same reaction products.The element diffusion of S570 was focused on the edge of the AST particles with partial loss of high entropy.Complete element diffusion and entire loss of high entropy of AST particles happened on H570.The differences in the microstructure caused by the three preparation methods led to the changes in mechanical properties and fracture mechanisms of composites.
基金supported by the National Research Foundation (NRF) of Korea (Nos. 2018R1D1A1B07051429 and 2020R1G1A1102692)。
文摘Al-doped ZnO(AZO) is considered as an alternative to transparent conductive oxide materials.Patterning and achieving a stable surface are important challenges in the development and optimization of dry etching processes, which must be overcome for the application of AZO in various devices. Therefore, in this study, the etch rate and surface properties of an AZO thin film after plasma etching using the adaptive coupled plasma system were investigated. The fastest etch rate was achieved with a CF_(4)/Ar ratio of 50:50 sccm. Regardless of the ratio of CF_(4) to Ar,the transmittance of the film in the visible region exceeded 80%. X-ray photoelectron spectroscopy analysis of the AZO thin film confirmed that metal-F bonding persists on the surface after plasma etching. It was also shown that F eliminates O vacancies. Consequently, the work function and bandgap energy increased as the ratio of CF-4 increased. This study not only provides information on the effect of plasma on AZO thin film, but identifies the cause of changes in the device characteristics during device fabrication.
基金Project(18JS060) supported by the Shaanxi Key Laboratory of Nano-materials and Technology,ChinaProject(2018JQ5087) supported by Natural Science Basic Research Plan of Shaanxi Province,China。
文摘Hypereutectic Al-40 wt.%Si alloys were fabricated by the combination of gas atomization and spark plasma sintering(SPS) technology. The effects of holding time(15-60 min) on phase composition, microstructure, density,mechanical properties of Al-Si alloys were investigated by XRD, SEM, a hydrostatic balance, an automatic micro hardness tester and a universal tensile testing machine. The results showed that homogenous distribution of ultrafine primary Si and high density of alloys can be obtained at holding time of 30 min. Compared with primary Si(3.7 μm)fabricated by gas atomization, the average size increased from 5.17 to 7.72 μm with the increase of holding time during SPS process. Overall, the relative density, maximum tensile strength and Vickers hardness of 94.9%, 205 MPa and HV;196.86 were achieved at holding time of 30 min, respectively. In addition, all the diffraction peaks were corresponded to α-Al or β-Si and no other phase can be detected. Finally, the densification process of SPS was also discussed.
