Microstructural evolution during annealing of the melt-spun ternary hypoeutectic Al-7.6Si-3.3Fe (in wt.%) alloy


Unlu N., GENC A., Ovecoglu M. L. , LAVERNIA E., FROES F.

JOURNAL OF ALLOYS AND COMPOUNDS, vol.343, pp.223-233, 2002 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 343
  • Publication Date: 2002
  • Doi Number: 10.1016/s0925-8388(02)00284-0
  • Title of Journal : JOURNAL OF ALLOYS AND COMPOUNDS
  • Page Numbers: pp.223-233

Abstract

A ternary hypoeutectic Al-7.6 wt.%Si-3.3 wt.%Fe alloy was rapidly quenched at cooling rates between 10(6) and 10(7) K/s using the melt-spinning technique. Differential scanning calorimetry (DSC) scan of the as-quenched ribbon revealed a small exothermic peak at 348degreesC, attributed to the silicon particle coarsening and two endothermic peaks: one at 585degreesC and the other at 600degreesC corresponding to ternary eutectic and liquidus transformation, respectively. On the basis of the DSC analyses, the as-quenched ribbons were annealed at T=390, 560, 600 and 632degreesC. The annealed ribbons were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. From the XRD scans, a solid solubility extension value of 1.75 at.% Si in alpha-Al was measured for the as-quenched ribbon and the beta-Al5FeSi intermetallic phase start temperature was determined as 560degreesC. TEM investigations revealed the coarsening of Si particles in the alpha-Al matrix and the increase of the alpha-Al5FeSi intermetallic phase particle size from 80 to 100 nm at the annealing temperature of 560degreesC to about 700 nm at the annealing temperature of 632degreesC. The microhardness value of the as-quenched hypoeutectic alloy was measured as 146 kg/mm(2) Which is 2.5 times more than that of the conventionally cast counterpart. The microhardness values decreased gradually with increase in annealing temperatures. (C) 2002 Elsevier Science B.V. All rights reserved.