The Zr-modified Al-Si-Cu-Mg alloy with 0.14wt%Zr addition was studied against the counterparts of commercially used EN-AC-42000 (Al7Si0.5Cu) baseline alloy for the effect of Zr on the high cycle fatigue (HCF) and mechanical properties at elevated temperatures of 150, 200, 250 o C. It was found that the fatigue life was significantly improved by 8-10 times at the high stress amplitude of 140 MPa in the Zr-modified alloy at all different temperatures. The

In order to develop alloys as the substitute of Pb-based materials for shielding materials in detonating and explosive cords, the materials requirement was analyzed and Sn-Cu based alloys were selected as candidates for this purpose. Four alloys including Sn-0.3wt.%Cu, Sn-0.5wt.%Cu, Sn-0.7wt.%Cu, and Sn-1.0wt.%Cu were processed from melting, casting, rolling, and annealing. The microstructure and mechanical properties of the alloys were investigated under as-cast, as-rolled and as-annealed conditions. The results confirmed that Sn-Cu based alloys are the appropriate substitute of Pb-based alloys for the application of detonating and explosive cords. The advantages of Sn-Cu alloys include resource abundant, low materials cost, non-toxicity for health and environment, relatively high density for supplying sufficient impulse energy and momentum for penetration, acceptable mechanical properties, and easy in melting, casting, extrusion, rolling and drawings. The microstructure of hypoeutectic Sn-Cu alloys was characterized by Sn-Cu solution and Sn-Cu6Sn5 eutectic phase. The annealing heat treatment was not able to modify the microstructure. The Sn-Cu based alloys with 0.3 to 1.0wt.%Cu offered the yield strength from 26.1 to 50.8MPa, ultimate tensile strength from 30.1 to 51.5MPa and elongation from 87.5 to 56.0%, which were comparable with the mechanical properties of the currently used Pb-based alloys. More importantly, Sn-Cu alloys exhibited strain softening under tensile stress, which was critically beneficial to the shielding manufacture and subsequent processing after assembly with high-energy explosive materials.

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Electrochemical corrosion behaviour of Sn-3Zn-xBi (x=0, 1, 3, 5, 7 wt.%) solder alloys were investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques, to explore the effect of Bi on corrosion performance of the Sn-Zn alloy. Results indicated that minor (1 wt.%) Bi addition increased the corrosion susceptibility, mainly attributed to the coarsened and more uniformly distributed Zn-rich precipitates, while further increasing Bi decreased the corrosion susceptibility due to the higher fraction of nobler Bi particles serving as anodic barriers. The Sn-3Zn-7Bi possessed the best corrosion resistance among all alloys. The role of Bi on corrosion was considerably discussed.

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