Microstructures and mechanical properties of heat-resistant high-pressure die-cast Mg―4Al―xLa―0.3Mn (x = 1, 2, 4, 6) alloys

Mg-4Al-xLa-0.3Mn (x = 1, 2, 4 and 6 wt.%) magnesium alloys were prepared successfully by the high-pressure die-casting technique. The microstructures, tensile properties in the temperature range from room temperature to 300 degrees C and heat resistance were investigated. It was confirmed that the Mg-Al-La-based alloys exhibited outstanding die-cast character. The cross-section of test bar could be divided into two parts by a narrow band, that is, the fine skin region and the relatively coarse center region. When addition of La reached 4 wt.%, the die-cast alloy exhibited high tensile properties and good heat resistance up until 200 degrees C. It was demonstrated that the outstanding mechanical properties were mainly attributed to the fine grain size and the strengthening phase Al11La3, which was in high volume fraction, fine acicular/lamellar morphology, "orderly stack" distribution and excellent thermal stability. The result of this research provided a basis for further investigation of the new high-pressure die-cast Mg-Al-RE alloys designed to serve at temperature up to 200 degrees C. (C) 2010 Elsevier B.V. All rights reserved.

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