Designing geometry of the magnesium-eutectic mixture layered composite
Renata Mola, Andrzej Dziadoń
Quarterly No. 4, 2009 pages 322-326
DOI:
keywords: layered composite, magnesium, intermetallic phases
abstract It has been shown that there is a possibility to make layered magnesium-eutectic mixture composite from the elemental magnesium and aluminium sheets. To obtain a composite, magnesium and aluminium sheets are formed alternately into a pocket and then heated at temperature of 445°C. Holding for a few minutes the magnesium-aluminium pocket leads to reaction between the metals in the liquid state. Because front of the reaction zone migrates mainly into the magnesium, more volume of magnesium than aluminium is consumed in the reaction course. Heating is prolonged till the aluminium is exhausted and transformed with part of the magnesium into a liquid phase. During solidification eutectic mixture is formed. As a result composite with layers of residual magnesium stocked between layers of eutectic mixture is produced. The eutectic mixture contains Mg17Al12 intermetallic compound, so these layers of the composite are the reinforcement layers. The thickness of the reinforcement layers depend on the amount of aluminium placed between the magnesium layers. Presented method allow to produce the composites with any thickness ratio of magnesium layers to the eutectic mixture layers by choosing the thick-ness ratio of starting magnesium and aluminium sheets. In this way structure and mechanical properties of the composite can be modeling. A paper contains analysis of the composite formation in the aspect of the designing geometry of the composite layers. The work was based on the experimental data. The thickness of the initial magnesium and aluminium sheets was selected to produce a series of composites with different thickness ratios between the composite layers. The resulting thickness of the eutectic mixture layers and thickness of the residual magnesium layers were measured using optical microscope. It was found that the layers of composite containing eutectic mixture are four times thicker than the thickness of aluminium sheets used for composite fabrication. Volume contribution of the magnesium in the eutectic mixture synthesized layers of the composite was also determined. On basis of the measurements, the simple relations between the thickness starting magnesium and aluminium sheets and the thickness of the resulting composite layers were formulated.