レオキャスト7075アルミニウム合金の半溶融押出し材の特性 [in Japanese] Extrusion of Rheocast 7075 Aluminum Alloys in Semi-Solid State [in Japanese]
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Two kinds of rheocast 7075 aluminum alloy small billets with a fine globular structure or a fine dendrite-dispersed one could be obtained by mechanical stirring at the position extremely near or slightly remote from the solid-liquid interface during solidification, respectively. At ram speed of 1 mm/s, both kinds of the rheocast billets could be extruded in semi-solid states to the round bars with smooth surfaces, while numerous surface cracks reaching inside generated at the case of the billets cast into metal mold. In all billets, extrusions were proceeded by some leaks of liquid phase, which resulted in the lowering of strength for the round bars by the significant loss of solute concentrations as zinc and copper in them. Such liquid leak was suppressed by increasing ram speed to 5 mm/s in the rheocast billet and the hardness of the bars after T6 treatment compared with the one for hot extrusion product.
- THE JOURNAL OF THE JAPAN FOUNDRYMEN'S SOCIETY
THE JOURNAL OF THE JAPAN FOUNDRYMEN'S SOCIETY 70(9), 641-647, 1998-09
Japan Foundry Engineering Society