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Li X.,Northeastern University China | Li X.,Chalco Ruimin Corporation | He L.,Northeastern University China | Pei Z.,Northeastern University China | And 3 more authors.
China Foundry | Year: 2013

The micro-porosity is usually present in the as-cast microstructure, which decreases the tensile strength and ductility and therefore limit the application of cast aluminum parts. Although much work has been done to investigate the effects of various casting parameters on the formation of porosity in various aluminum alloys, up to now, little information has been available for the relationship between micro-porosity and tensile properties of 6063 alloy. In this study, the influences of size and area fraction of micro-porosity on the tensile properties and fracture behavior of 6063 aluminum alloy were investigated by means of tensile testing, optical microscopy (OM), and scanning electron microscopy (SEIVI). The tensile tests were conducted in air at 100 °C, 200 °C and 300 C, respectively. Results show that the large micro-porosity with sizes between 100 μm and 800 pm located at the center and top of the ingot, while the small micro-porosity with size between 2 pm and 60 pm distributed at the edge and bottom of the ingot. The area fraction of micro-porosity at the center of the ingot is much bigger than that at the edge of the ingot. When tested at 100 °C, with the decrease in the area fraction of micro-porosity from the top of the ingot to the bottom of the ingot, the ultimate tensile strength, yield strength and the elongation are increased from 82 to 99 MPa, 32 to 66 IVlPa and 7% to 11%, respectively. When the temperature is no more than 200 °C, the strain hardening exponent decreases with an increase in the area fraction of micro-porosity; while the deviation disappears when the temperature reaches 300 °C. The fracture mode of the alloy is greatly influenced by the size and area fraction of the micro-porosity.


Li X.H.,Northeastern University China | Li X.H.,Chalco Ruimin Corporation | Cao Y.H.,Northeastern University China | He L.Z.,Northeastern University China | And 2 more authors.
Advanced Materials Research | Year: 2013

The property and microstructure of pure Al prepared by the cryogenic ECAP after annealing at different temperatures and times with and without the application of 12T high magnetic field were investigated by hardness test and optical microscopy observation. The results show that with the application of high magnetic field, the hardness of cryo-ECAPed pure Al is lower than that of material annealing without high magnetic field. The high magnetic field accelerates crystallization of cryo-ECAPed pure Al during annealing. © (2013) Trans Tech Publications, Switzerland.


He L.,Northeastern University China | Li X.,Northeastern University China | Li X.,Chalco Ruimin Corporation | Zhu P.,Northeastern University China | And 3 more authors.
Materials Characterization | Year: 2012

The evolutions of coarse constituent phases in homogenized 7085 aluminum alloy at different conditions with or without the application of 12 T high magnetic field were examined by using differential scanning calorimetry, scanning electronic microscope, energy dispersive spectroscopy and X-ray diffraction. It is found that the main constituent phases including quaternary phase T(AlZnMgCu), Al 7Cu 2Fe, and AlTiCuFeSi are present in as-cast 7085 alloy. During homogenization, α + T eutectics become discontinuous and spheroidized, and Al 2CuMg phase nucleates and grows along α + T eutectics. High magnetic field significantly accelerates the melting of quaternary phase T and Al 2CuMg phase. When the alloy homogenized at 460 °C/10 h + 480 °C/8 h with 12 T magnetic field, the least amount of constituent phases is obtained. © 2012 Elsevier Inc. All rights reserved.


Li X.,Northeastern University China | Li X.,Chalco Ruimin Corporation | He L.,Northeastern University China | Cao Y.,Northeastern University China | And 3 more authors.
Advanced Materials Research | Year: 2012

The influences of cooling rate, hydrogen inflating time, degassing time, inclusion content on the distribution of pores within the ingot, hydrogen content and the mechanical properties of 1050 aluminum alloy were investigated by tensile test, optical microscope(OM), scanning electron microscope(SEM). With the increasing inflating hydrogen time, the hydrogen content increases, while, the strengths and elongation decrease. With the increasing degassing time, the hydrogen content decreases, while, the strengths and the elongation increase. With increasing cast temperature, the hydrogen content remains constant at first and increases obviously from 7200C to 7600C, while the strengths and the elongation decrease gradually. The crack is mainly originated at outcrop of slip step, inclusion and porosity.


He L.,Northeastern University China | Li X.,Chalco Ruimin Corporation | Zhang H.,Northeastern University China | Cui J.,Northeastern University China
69th World Foundry Congress 2010, WFC 2010 | Year: 2010

The microstructural evolutions of 7085 alloy during high magnetic field homogenization were investigated. The as-cast microstructures of 7085 alloy consist of eutectics α + AlZnMgCu, Al7CU2Fe, and AITiCuFe. During homogenization, α + AlZnMgCu eutectics become discontinuous and spheroidized, some transform into Al2CuMg( S). High magnetic field significantly accelerates the melting of AlZnMgCu and S phase. The optimum homogenization result is obtained at 460°C/10 h +480°C/8 h under 12 T magnetic field.

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