In-situ method for the investigation of equiaxed grain growth in hypoeutectic and hypereutectic Al-Si alloys

Journal Article · Tue Apr 14 04:00:00 EDT 1998 · Scripta Materialia

DOI:https://doi.org/10.1016/S1359-6462(98)00069-4· OSTI ID:619501

Pekguleryuz, M O; Pedneau, N ^[1]

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1. Univ. of Quebec, Chicoutimi, Quebec (Canada)

There are few experimental and kinetic studies of equiaxed-dendrite nucleation and growth in the mushy zone during the solidification of liquid metal alloys. Existing studies have either tried to deduce the solidification kinetics and mechanism from the final as-cast structure or to simulate the development of the grain structure using transparent organic solutions. These methods have short-comings in that they cannot account for various phenomena such as dendrite fragmentation, coarsening or grain refining. Pedneau et al have recently developed a method for the in-situ and real-time investigation of equiaxed-grain growth in the mushy zone during solidification. The method is based on the Electrical Sensing Zone (ESZ) technique, and allows for the monitoring of the density and size distribution of equiaxed grains in aluminum alloys during solidification. In this paper, the application of the ESZ method to monitor equiaxed grains within the mushy range of Al-Si alloys is described. When the alloy is within the hypoeutectic region of the Al-Si binary system, the first equiaxed grains to form are primary {alpha}-Al which are more conductive than the melt in which they form. Hence G(k) is negative and negative pulses are obtained. When the alloy is within the hypereutectic range, the first phase to form is the primary silicon which is of much higher resistivity than the liquid aluminum. Then, G(k) equals one and positive pulses are obtained.

• OSTI ID: 619501
• Journal Information: Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 10 Vol. 38; ISSN 1359-6462; ISSN SCMAF7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
DIAGNOSTIC TECHNIQUES
GRAIN GROWTH
SILICON ALLOYS
SOLIDIFICATION