Mg , Si and die geometry effects on the formability and the machinability of recycled aluminium alloys
Mg, Si and die geometry effects on the formability and machinability were experimentally reported, concerning AA6xxx aluminium alloys which were produced by recycling raw material. The aluminium alloys formability characteristics were evaluated during extrusion and open die forging tests estimating the needed load; the machinability characteristics of the same aluminium alloys were conducted via cutting force measurements during simple turning process. Key-Words: formability, machinability, Mg ratio, Si ratio, extrusion test, cutting, recycling
Formation of die lines during extrusion of AA6063
AbstractThe die line phenomenon during extrusion of AA 6063 has been investigated and the effects of temperature and strain rate established. The influence of die land length on the surface generated features was also determined. The results indicate that the surface formation mechanism is one of generation and modification; the surface is generated on the leading edge of the die land in the absence of oxygen and interacts thereafter with the remainder of the die land, resulting in material transfer between extrudate and die land, thus increasing the surface roughness. Two mechanisms were identified, both of which involved extrudate die land interaction. The aluminium film on the forward portion of the die land was observed to be more stable and its morphology wasfound to relate directly to the die line features. From these trials, optimum process conditions together with a minimum die land length were identified. Processing at the optimum conditions continued to generate die lines, but these were observe...
Unidirectional hexagonal rare-earth disilicide nanowires on vicinal Si(100)-2×1
Rare-earth disilicide nanowires grown on vicinal Si(100) with a miscut of 2–2.5° toward the [110] azimuth at 600 °C were studied by scanning tunneling microscopy and compared with those grown on flat Si(001). In contrast to rare-earth disilicide nanowires grown on flat Si(100) surfaces, the nanowires grow unidirectionally along the [01̄1] direction of the vicinal Si(100) surface. Rare-earth disilicide nanowires form bundles composed of single nanowire units on both flat and vicinal surfaces. Yet, on the vicinal surface, the bundle width is comparable to the width of the terrace. The average nanowire length on the vicinal substrate is longer than that on the flat substrate. Scanning tunneling spectroscopy shows that the rare-earth disilicide nanowires have metallic properties.