Papers by Keyword: Al-Mg Alloys

Abstract: Recently, high efficiency and performance have become necessary attributes of information equipment such as laser printers. Thus, demand has increased for optical scanning parts that reduce optical aberration, scatter, and diffraction are required in laser printers. Polygon mirrors are manufactured by polishing a plating or glassy material to a mirror finish. In this study, we shortened the manufacturing process to improve the productivity and ultra-precision cutting technology of polygon mirrors made of aluminum. Thus, we had to reduce the geometric surface roughness achieved by mirror-cutting Al-Mg alloy and remove tear-out and scratch marks that occur during the cutting process. We investigated the cutting edge shape by using a straight diamond tool to decrease the surface defects produced during the ultra-precision cutting of Al-Mg alloy. We examined the mechanism for the occurrence of scratch marks and a method to reduce them. First, we measured the shape of the scratch marks and the cross-section with a scanning electron microscope. We found the tool collides with crystallization to produce small pieces, which then cause scratch marks. We developed a triple-facet tool with a double-facet at the end cutting edge to remove scratch marks and investigated the influence of surface defects. We clarified that using the triple-facet for a tool setting angle of 0° to 0.04° could achieve a good-quality machined surface without tear-out and scratch marks. In addition, the undeformed chip thickness was less than 80 nm

Abstract: A series of Al-3.2Mg alloys with addition of 0~1.6 wt.% rare earth (Ce and La) were prepared. The microstructure of as-cast Al-3.2Mg alloys was investigated by optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and the tensile strength was measured. The results indicated that the addition of rare earth elements refined grain size and secondary dendrite arm spacing (SDAS), and the tensile strength was affected by means of the second-phase precipitation and the grain boundary. Accordingly, the ductility of Al-3.2Mg alloys reduced with the increasing of R_E addition due to the more second-phase formation.

Abstract: Al-Mg alloys developed for auto body sheets with different Cu contents were fabricated in the laboratory scale. The effects of Cu content on the microstructures, formability and Portevin–Le Chatelier(PLC) effect of the alloys were investigated by polarizied optical microscopy and room temperature tensile testing. It has been found that with increasing Cu content, there was little change of the strain hardening exponent, but the plastic strain ratio and limiting drawing ratio increased firstly and then decreased. A quantitative statistical analysis of the characteristics of the PLC effect was made, including the stress drop and the reloading time, which follow a common linear relationship with plastic strain, and the increase rate of stress drop and reloading time was bigger with more Cu content. A detailed discussion of the corresponding mechanism of Cu and Cu-containing precipitates on the dynamic strain aging(DSA) was made.