Environmentally Benign Fabricating Process of Magnesium Alloy by Cyclical Plastic Working in Solid-State

Abstract

Solid-state processing via cyclically plastic working to output the green compact has been developed to fabricate magnesium alloys with fine microstructures. The relationship between the energy consumption during the plastic working and the characteristics of hot extruded magnesium alloys was evaluated from the viewpoint of the environmentally benign process. The cyclical plastic working marks a significant advance in refining microstructures, such as matrix grain and silicon particles added to synthesize Mg 2 Si via solid-state reaction with magnesium. For example, the grain size of hot extruded AZ31 alloy is 3-15 mm, which is remarkably smaller than that with 20-80 mm in employing the cold compact without using such a plastic working. As a result of the grain refinement, AZ31 alloys reveal higher UTS of 330-355 MPa than the conventional alloys of 270 MPa. The energy consumption of the cyclical plastic working with 200 cycles is 10 kJg À1 to fabricate the billet consolidated by hot extrusion, when using a high-speed screw-driven press machine. This is less than 10% of the energy consumed by the conventional recycling process in re-melting wasted magnesium alloys (126 kJg À1 ). This process is highly capable of producing high performance magnesium alloys with a small energy consumption and is environment-friendly.

Synthesis of Mg2Si1−xSnx solid solutions as thermoelectric materials by bulk mechanical alloying and hot pressing

“…In the mechanical milling and grinding, such as mechanical alloying (MA), this self-heating synthesis is mechanically activated by intense loading and straining. The starting elemental powder mixture is refined with milling in the vial so that the reaction takes place in the solid state and the refinement process is followed by abrupt solid-state reaction after an incubation time [13][14][15][16]. However, these mechanical milling and grinding processes have to suffer from long processing time, oxidation and various contaminations in general [17][18][19][20].…”

Cold repeated forming of compact for aluminium foam

“…Severe plastic deformation of metals has been recently investigated to obtain fine grains (Azushima et al, 2008). Kondoh and Aizawa (2003) have been developed a cold repeated compaction process of magnesium powder to produce fine grain magnesium. In this process, powder particles are subjected to severe plastic deformation by repeating backward extrusion and compression.…”

Tribological Analysis of Mg2Si Particulates Reinforced Powder Metallurgy Magnesium Alloy Composites under Oil Lubrication Condition

“…Fine Mg 2 Si powder with a mean particle size of 8.2 μm was obtained by ball milling (SEIWA GIKEN Co., RM-30) for 7.2 kiloseconds in air. Figure 1 [16], was applied to the elemental mixture to refine Mg 2 Si particles and uniformly distribute them over the matrix of the green compact. In RPW process, the alternate operation between cold compaction and backward extrusion (an extrusion ratio; 5.2) was carried out on the powder mixture filled in the die, which was installed in a 1000 kN screw-driven press machine.…”