EFFECT OF CU CONTENT AND GROWTH VELOCITY ON THE MICROSTRUCTURE PROPERTIES OF THE DIRECTIONALLY SOLIDIFIED AL-MN-CU TERNARY ALLOYS

Abstract

In this work, influences of composition (Cu content) and growth velocity (V) on the microstructure (dendritic spacing) of Al–Mn–Cu ternary alloys have been investigated. Al–1.9Mn–xCu (x=0.5, 1.5 and 5 wt. %) alloys were prepared using metals of 99.90% high purity in the vacuum atmosphere. These alloys were directionally solidified upwards under various growth velocities (8.3–978 m/s) using a Bridgman-type directional solidification furnace at a constant temperature gradient (7.1 K/mm). Measurements of primary dendrite arm spacing () of the samples were carried out and then expressed as functions of growth velocity and Cu content. Especially, cell-dendritic transition was detected for low growth velocity (41.6 m/s) for alloys containing 0.5 and 1.5Cu. It has been found that the values of  decrease with increasing V and decreasing Cu content. Keywords: Aluminum alloys, Solidification, Cell-dendritic transition, Dendrite arm spacing