Advanced Materials Research Vols. 652-654

Abstract: SUSXM7 Cu-bearing austenitic stainless stee1 was conducted with special antibacterial heat treatment and antibacterial properties of the steel were studied. The experimental results show that a suitable amount of ε-Cu phases can precipitate from the matrix of SUSXM7 steel after solution treated at 1100 °C and aging treated at 650 - 850 °C. ε-Cu phases are granular with diameter of 100 - 200 nm. SUSXM7 Cu-bearing austenitic stainless steels possess excellent antibacterial properties. Antibacterial rates against two typical bacteria of Escherichia coli and Staphylococcus aureus surpass 99.0％ and are basically equal to that of Cu-bearing austenitic antibacterial stainless steel researched widely now.

Abstract: To investigate the interaction between Reduced Activation Ferritic Martisitic steel (RAFMs) and deuterium produced by the plasma in Tokamak, iron was implanted deuterium ions at RT, then aged at 773K for 1h. Finally it was irradiated with 1250keV electrons in high voltage electronic microscope (HVEM) at 773K. The result shows that dense small bubbles appeared on surface of iron in the form of convex lens after aged. The bubbles have tended to distribute along some line in grain body. Electron irradiation at 773K resulted in a greater size and a smaller density of bubbles with the increasing dose. Bubbles continued to grow up and broke. Lateral stress drive theory indicates the evolution of bubbles on surface in iron is mainly attributed to lateral stress caused by irradiation.

Abstract: Red scale is the main surface defect of hot-rolled silicon steel plate due to the formation of fayalite. Studies have been done on high temperature oxidation of Fe-Si alloy, but effect of temperature on structure of outer Fe oxide layer is not fully discussed. Thermogravimetric analyzer (TGA) was used to simulate isothermal 60-min oxidation process of Fe-2.2Si alloy under air condition at 700°C-1200°C. Cross-sectional scale morphology and elemental distribution of the oxide layer were investigated by electron probe microanalysis (EPMA). It is found that in order to observe internal oxide precipitates clearly it is helpful that the sample is etched with nitric acid solution in alcohol firstly and then etched with hydrochloric acid solution in alcohol. At 700°C-1150°C outer Fe oxide layer is mostly composed of Fe2O3 and at 1200°C it consists of FeO + Fe3O4 + Fe2O3 + mixture of FeO/Fe2SiO4.

Abstract: Discuss how iron, copper and magnesium alloy and rare earth cerium influence the electrical and mechanical properties of aluminum conductor using the orthogonal test, to thereby get the best alloy composition that meets the requirement; through test analysis on the conductivity, intensity and elongation at break of aluminum conductor with the best alloy composition, discuss the influence of different annealing temperature and holding time on their performance. The results show that: the best material composition of the aluminum alloy conductor would be 0.25% Fe, 0.40% Cu, 0.05% Mg, 0.30% Ce, 0.008% B, and aluminum and inevitable impurities. The intensity, elongation at break and conductivity of this aluminum conductor would be 110N/mm2, 30.0% and 62.2%IACS respectively. The best annealing process parameters are annealing temperature of 310°C, and holding time for 30min, direct air cool. The intensity of aluminum conductor processed is 129 N/mm2, and the elongation at break, resistivity, and conductivity are 15.0%, 2.782×10-8Ω•m and 62%IACS respectively. The mechanical properties and conductivity of this aluminum conductor both comply with the requirements of wire and cable conductor cores.

Abstract: The paper discussed the effects of Ce, Mn, Cr on the microstructure and properties of high-iron eutectic Al-Si piston alloy using orthogonal design. It has been found that Mn and Cr improved the morphology of β phase (Al9FeSi3), becoming the Fe phase that consists of Mn and Cr; Rare earths Ce has a strong effect on refinement of the eutectic silicon. At a high mass fraction of Ce, Ce enter Fe phase that contains Mn and Ce, which improves its morphology greatly and decreases the size of Fe phase, and is able to replace the position of Ni, becoming high-temperature Al-Ni-Cu-Ce phase. The best additions of Ce, Fe, Mn, Cr would be 0.8%, 1.0%, 0.4% and 0.1% respectively and the tensile strength under room temperature (25°C) and high temperature(300°C) would reach 270.3MPa and 136.7MPa respectively, which fully meet the requirements of the use of novel the piston high temperature load.

Abstract: The regression equation of the relationship between Si, Cu and Mg and the mechanical properties of Al-Si-Cu-Mg alloy was established according to the orthogonal experimental results. The microstructure of the Al-Si-Cu-Mg alloy was analyzed with scanning electron microscopy and energy dispersive spectroscopy. The results show that Si, Cu and Mg affected the mechanical properties (tensile strength and elongation rate) at 250 °C most significantly, minimally and negatively, respectively. The interactions between Cu, Mg and Si greatly reduced the high-temperature tensile strength owing to the formation of brittle and hard intermetallic Al₅Mg₈Cu₂Si₆ that behaved as the initial crack during stretching.

Abstract: The main task of this work was to study the effects of aging time and aging temperature on the microstructure and mechanical properties of 6082 aluminum alloy extrusions. Artificial aging was performed on the alloy extrusions at the temperatures of 150, 175 and 200 °C for the aging times of 4, 8 and 12 h. The microstructure evolution of the aluminum alloy extrusions with increase of the aging time and temperature was investigated by Field Emission Scanning Electron Microscope (FESEM). For the purpose of how the aging process affected the mechanical properties, tensile tests were performed. The results showed that the optimum aging treatment was 175 °C/4 h. Under this condition, the tensile strength (Rm) and the yield strength (Rp) in the longitudinal direction of the extrusions reached the maximum value more than 350MPa and 320MPa, respectively, and the tensile elongation (A) was more than 15%.

Abstract: The valence electron structures and bond energies of Al3Ti, Al3Zr, TiB2 and ZrB2 are studied based on the empirical electron theory of solids and molecules (EET theory), giving theoretical explanation on the different microstructure with different atomic number ratio of Ti, Zr and B in aluminum alloys. It is demonstrated that the formation of TiB2 and ZrB2 have priority for their bond energies are stronger than that of Al3Zr and Al3Ti. In addition, refining effect of Al3Ti and Al3Zr to Al is better.

Abstract: In the present work, the effects of heat treatment on microstructure and mechanical properties of A390 alloy were investigated. The results show that the as-cast microstructure of A390 alloy mainly consists of primary silicon, α-Al, eutectic silicon and Al₂Cu phase. The morphology of primary silicon is irregular polygonal block with sharp edges. Eutectic silicon exhibits a coarse plate-like and acicular morphology and the fishbone like Al₂Cu phases are gathered at the grain boundary. During solution treatment, eutectic silicon undergoes fragmentation and spheroidization and T6 heat treatment has a profound effect on the dissolution of Cu and Mg. However, the morphology and size of primary silicon changes little. After the aging process, Al₂Cu phases are precipited as lamellar morphology. As a result, the mechanical properties the heat treated A390 alloy increases significantly after T6 treatment.

Abstract: A series of wedge shape Fe24+XCo24-XCr15Mo14C15B6Y2 (x=0,2,4,6,8) samples were prepared by copper mold suction casting method. The effects of high Co contents on glass forming ability (GFA) and mechanical properties of Fe24+XCo24-X Cr15Mo14C15B6Y2 bulk metallic glasses (BMG) were investigated, respectively. The glass forming ability of bulk amorphous Fe24+XCo24-XCr15Mo14C15B6Y2 (x=0,2,4,6,8) and Fe41Co7Cr15Mo14C15B6Y2 alloys have been researched. Simultaneously, the thermal conductivity parameters of those alloys were tested. The maximum thickness of amorphous region of wedge-shaped samples are dm =7.80 mm for Fe28Co20Cr15Mo14C15B6Y2, dm =7.10 mm for Fe41Co7Cr15Mo14C15B6Y2 and the thermal conductivity are λ=7.11 w.m-1.k-1 and 7.19 w.m-1.k-1, the thermal diffusivity are α=1.875 mm2/s and 1.905 mm2/s for Fe28Co20Cr15Mo14C15B6Y2 and Fe41Co7Cr15Mo14C15B6Y2 BMGs, respectively. The glass forming ability of Fe28Co20Cr15Mo14C15B6Y2 alloy is bigger than that of well known Fe41Co7Cr15Mo14C15B6Y2 alloy. With the change of Co content, the Vickers hardness of Fe24+XCo24-XCr15Mo14C15B6Y2 (x=0,2,4,6,8) change from 1292 to 1322Hv.