期刊文献+
共找到9篇文章
< 1 >
每页显示 20 50 100
Characteristics and distribution of microstructures in high pressure die cast alloys with X-ray microtomography:A review
1
作者 hai-dong zhao Xue-ling Wang +2 位作者 Qian Wan Wen-hui Bai Fei Liu 《China Foundry》 SCIE EI CAS CSCD 2024年第5期427-444,共18页
Al and Mg alloy high pressure die castings(HPDC)are increasingly used in automotive industries.The microstructures in the castings have decisive effect on the casting mechanical properties,in which the microstructure ... Al and Mg alloy high pressure die castings(HPDC)are increasingly used in automotive industries.The microstructures in the castings have decisive effect on the casting mechanical properties,in which the microstructure characteristics are fundamental for the investigation of the microstructure-property relation.During the past decade,the microstructure characteristics of HPDC Al and Mg alloys,especially micro-pores andα-Fe,have been investigated from two-dimensional(2D)to threedimensional with X-ray micro-computed tomography(μ-CT).This paper provides an overview of the current understanding regarding the 3D characteristics and formation mechanisms of microstructures in HPDC alloys,their spatial distributions,and the impact on mechanical properties.Additionally,it outlines future research directions for the formation and control of heterogeneous microstructures in HPDC alloys. 展开更多
关键词 high pressure die casting microstructure three-dimensional characteristics DISTRIBUTION Al and Mg alloys
下载PDF
Strength and ductility optimization of HPDC AlSi8MgCuZn2 alloys by modifying pre-aging treatment
2
作者 Yuan-hang Jiang Hui-ting Zheng +1 位作者 Fei Liu hai-dong zhao 《China Foundry》 SCIE EI CAS CSCD 2024年第4期343-351,共9页
Considering the components produced by high pressure die casting(HPDC)process usually with ultra-large sizes and complex morphologies,high temperature solid solution treatment is not a suitable method to further impro... Considering the components produced by high pressure die casting(HPDC)process usually with ultra-large sizes and complex morphologies,high temperature solid solution treatment is not a suitable method to further improve their mechanical properties.In this study,two-stage aging treatment with different pre-aging times was designed and employed to further improve the mechanical properties of HPDC Al8SiMgCuZn alloy.The characteristics of precipitates were evaluated by a transmission electron microscope(TEM),and the precipitation strengthening mechanism was discussed.The results reveal that the strengthening is mainly contributed by the precipitation ofβ″phase after two-stage aging,and the number density and size of the precipitates are significantly depended on the pre-aging time.The number density of precipitates is increased with the pre-aging time prolonged from 0 h to 4 h,and then decreases with the further increase of pre-aging time from 4 h to 6 h.The precipitates with the highest density and smallest size are observed after pre-aging for 4 h.After pre-aged at 100℃for 4 h and then artificial aged at 200℃for 30 min,the yield strength of 207 MPa,ultimate tensile strength of 325 MPa and elongation of 7.6%are achieved. 展开更多
关键词 high pressure die cast aluminum alloy microstructural heterogeneity mechanical properties precipitation strengthening two-stage aging
下载PDF
Three-dimensional characteristics of Fe-rich intermetal ics in gravity-cast Al-6Si alloys 被引量:4
3
作者 Chen Hu Wen-feng Luo hai-dong zhao 《China Foundry》 SCIE 2017年第5期379-385,共7页
Fe-rich intermetallics, especially β-Fe phase, usually forming in the microstructure of cast aluminum alloys, are very detrimental to mechanical properties. In the present work, the effects of Fe content on phase tra... Fe-rich intermetallics, especially β-Fe phase, usually forming in the microstructure of cast aluminum alloys, are very detrimental to mechanical properties. In the present work, the effects of Fe content on phase transformation and microstructures were analyzed using a 3D X-ray microscope. Based on the highresolution 3D X-ray computed tomography, the 3D characteristics of Fe-rich intermetallics and micropores in the gravity-cast Al-6 Si alloys with different Fe contents were investigated. In addition, the effect of intermetallics on the microporosity was discussed. The results show that with increasing the Fe content from 0.10 wt.% to 0.60 wt.%, the volume fraction of Fe-rich intermetallics and the volume of the largest size Fe-rich intermetallic increased, and the 3D morphology of intermetallics changed from fine flake to network aggregation. As the Fe contents increased, the shrinkage pores were characterized, which were rather complex due to the micropores promoted by the intermetallics interactions. 展开更多
关键词 Fe-rich intermetallics 3D X-ray computed tomography MICROPORES Al-Si alloy
下载PDF
Influence of intensification pressures on pores in die-cast ADC12 alloys 被引量:2
4
作者 Chun-tao Wang Jie Yao +1 位作者 hai-dong zhao Run-sheng Yang 《China Foundry》 SCIE 2019年第3期184-189,共6页
Die casting process is widely applied in making Al parts. However, due to high speed of liquid metal flow in the die cavity, gases are prone to be entrapped in the filling, resulting in porosity defects. The X-ray com... Die casting process is widely applied in making Al parts. However, due to high speed of liquid metal flow in the die cavity, gases are prone to be entrapped in the filling, resulting in porosity defects. The X-ray computed tomography scanning technique was used to detect the pores in die-cast ADC12 alloys with different intensification pressures. The three-dimensional features of pores including pore size, number, sphericity have been obtained. The effect of different intensification pressures on two different kinds of pores, namely gas-pores and shrinkage pores, was analyzed. The results show that with increasing the pressure, the pore fractions and quantity gradually decrease. When the pressure increased to 85 MPa, the pores from gas entrapment during the mold filling were compressed, leading to a lower porosity fraction. The pressure cannot affect the pores in the samples with a thin wall (2 mm) due to a great solidification rate. 展开更多
关键词 die CASTING INTENSIFICATION pressure POROSITY X-ray COMPUTED tomography
下载PDF
Spatial interfacial heat transfer and surface characteristics during gravity casting of A356 alloy 被引量:2
5
作者 Jia-hua LIN hai-dong zhao Jia-min HUANG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2019年第1期43-50,共8页
As one of the key boundary conditions during casting solidification process, the interfacial heat transfer coefficient (IHTC) affects the temperature variation and distribution. Based on the improved nonlinear estimat... As one of the key boundary conditions during casting solidification process, the interfacial heat transfer coefficient (IHTC) affects the temperature variation and distribution. Based on the improved nonlinear estimation method (NEM), thermal measurements near both bottom and lateral metal-mold interfaces throughout A356 gravity casting process were carried out and applied to solving the inverse heat conduction problem (IHCP). Finite element method (FEM) is employed for modeling transient thermal fields implementing a developed NEM interface program to quantify transient IHTCs. It is found that IHTCs at the lateral interface become stable after the volumetric shrinkage of casting while those of the bottom interface reach the steady period once a surface layer has solidified. The stable value of bottom IHTCs is 750 W/(m^2·℃), which is approximately 3 times that at the lateral interface. Further analysis of the interplay between spatial IHTCs and observed surface morphology reveals that spatial heat transfer across casting-mold interfaces is the direct result of different interface evolution during solidification process. 展开更多
关键词 A356 alloy SOLIDIFICATION interfacial heat transfer coefficient inverse heat conduction problem surface characteristics
下载PDF
Simulation of α-Al grain formation in high vacuum die-casting Al-Si-Mg alloys with multi-component quantitative cellular automaton method 被引量:2
6
作者 Yong-zhi Hao hai-dong zhao +2 位作者 Xu Shen Xue-ling Wang Hui-ting Zheng 《China Foundry》 SCIE CAS 2022年第2期99-108,共10页
Al-Si-Mg alloys are the most commonly used material in high vacuum die-casting(HVDC),in which the morphology and distribution ofα-Al grains have important effect on mechanical properties.A multi-component quantitativ... Al-Si-Mg alloys are the most commonly used material in high vacuum die-casting(HVDC),in which the morphology and distribution ofα-Al grains have important effect on mechanical properties.A multi-component quantitative cellular automaton(CA)model was developed to simulate the microstructure and microsegregation of HVDC Al-Si-Mg alloys with different Si contents(7%and 10%)and cooling rates during solidification.The grain number and average grain size with electron backscatter diffraction(EBSD)analysis were used to verify the simulation.The relationship between grain size and nucleation order as well as nuclei density was investigated and discussed.It is found that the growth of grains will be restrained in the location with higher nuclei density.The influence of composition and cooling rate on the solute transport reveals that for AlSi7Mg0.3 alloy the concentration of solute Mg in liquid is higher at the beginning of eutectic solidification.The comparison between simulation and experiment results shows that externally solidified crystals(ESCs)have a significant effect for samples with high cooling rate and narrow solidification interval. 展开更多
关键词 Al-Si-Mg alloys high vacuum die-casting cellular automaton α-Al grains external solidification crystals
下载PDF
SMS Notifying Design in Intra-Day Scheduling Security Check System
7
作者 Cui-Hui Yan Licheng Sha +1 位作者 Sai Dai hai-dong zhao 《Energy and Power Engineering》 2017年第4期535-543,共9页
In order to master the future operation and stability of power grid exactly, and gasp the weak point accurately, the requirement of power data quality become strict, and the data timeliness of power gird change into o... In order to master the future operation and stability of power grid exactly, and gasp the weak point accurately, the requirement of power data quality become strict, and the data timeliness of power gird change into outstandingly more and more, because of this, in this paper propose the SMS notifying method of intra-day scheduling data based on safely data principle. The principle is mainly complied with the data source existed or not, the data is coincident to the power grid model, the data is unbroken or not and it is reasonable with the physical reality, then it can obtain better convergence and reasonable intra-day check power data. In order to accelerate the information and network pace of the power grid, the SMS notifying can monitoring data quality without time delay. It dredge the vast path for the future power market into use with the wide range, then, can more effective to ensure the convergence and accuracy of safe check calculation, it provides an effective guarantee with the safe and stable operation of the power grid, in the same way, it is also an efficient method to provides effective guarantee for power grid safe operation from the data source. 展开更多
关键词 SECURITY CHECKING Intra-Day SCHEDULING SMS Notifying
下载PDF
Improvement of impact properties of Al-Si-Mg alloy via solution treatment and joint modification with Sr and La
8
作者 Xiong-Ling Zheng Shao-Xiang Li +3 位作者 Jia-Le Ma Qing-Yan Xu hai-dong zhao Zhi-Qiang Han 《Rare Metals》 SCIE EI CAS CSCD 2024年第7期3301-3313,共13页
An effort to obtain superior impact properties for Al-7Si-0.35 Mg alloy is presented,where modification with 0.02 wt% Sr and 0.1 wt% La as well as solution treatment was jointly employed.The samples were solution trea... An effort to obtain superior impact properties for Al-7Si-0.35 Mg alloy is presented,where modification with 0.02 wt% Sr and 0.1 wt% La as well as solution treatment was jointly employed.The samples were solution treated at 535℃ for 15 min to 12 h.The microstructure,fracture mechanism,and their correlation with the impact properties of the alloy were studied in detail mainly through optical microscopy(OM),scanning electron microscopy(SEM) and oscillography impact test.The results show that the addition of Sr and La refined the eutectic Si particles significantly from~ 2.05 μm(modified with Sr alone) to~ 0.75 μm in as-cast microstructure,leading to a very homogeneous distribution of spheroidized Si particles in the alloy solution treated at 535℃ for 8 h.The alloy exhibits excellent impact toughness up to 75 J·cm^(-2),which is much higher than the maximum impact toughness of the alloys modified by Sr alone(~ 46 J·cm^(-2)).The major reason for this remarkable increase in the impact property is the dramatic increase in crack initiation energy.The dispersoid-free zones(DFZs)near the eutectic regions mainly consist of the ductile Al-matrix,which exhibits excellent ductility.The ductile Al-matrix of the DFZs hinders the crack propagation,resulting in a significant increase in crack propagation energy. 展开更多
关键词 Aluminum alloys MODIFICATION Solution treatment Microstructure Impact properties Fracture mechanism
原文传递
Greatly enhanced mechanical properties of thermoelectric SnSe through microstructure engineering 被引量:2
9
作者 Chen Chen Bin-Hao Wang +9 位作者 Chen Chen hai-dong zhao Bin Zhang Dan Wang Tao Shen Peng-Hui Li Song zhao Dong-Li Yu Yong-Jun Tian Bo Xu 《Journal of Advanced Ceramics》 SCIE EI CAS CSCD 2023年第5期1081-1089,共9页
The outstanding thermoelectric material, SnSe, is also known for its inferior mechanical properties, which bring great inconvenience for its application in thermoelectric devices. In this work, SnSe bulks were prepare... The outstanding thermoelectric material, SnSe, is also known for its inferior mechanical properties, which bring great inconvenience for its application in thermoelectric devices. In this work, SnSe bulks were prepared via a sequential procedure of high-pressure synthesis (HPS), ball milling, and spark plasma sintering (SPS). The produced polycrystalline samples with a unique microstructure of tightly-bound quasi-equiaxed grains exhibited excellent mechanical properties. The Vickers hardness (HV), compressive strength (σ_(c)), and bending strength (σ_(b)) reached 1.1 GPa, 300 MPa, and 90 MPa, respectively, all of which are far superior to those of ordinary polycrystalline SnSe. Furthermore, the microstructures did not deteriorate thermoelectric performance. This work demonstrated an effective procedure to prepare polycrystalline microstructure-engineered SnSe materials, which not only show advantages in device applications but also shed light on property enhancement for other layer-structured thermoelectric materials. 展开更多
关键词 thermoelectric materials SnSe mechanical properties HARDNESS
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部