The development of nucleation controlled microstructures during laser treatment of Al-Si alloys

Journal Article · Mon Jul 01 04:00:00 EDT 1996 · Acta Materialia

DOI:https://doi.org/10.1016/1359-6454(95)00393-2· OSTI ID:264090

Gremaud, M ^[1]; Allen, D R; Perepezko, J H ^[2]; Rappza, M ^[3]

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1. Calcom SA, Lausanne (Switzerland)
2. Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering
3. Swiss Federal Inst. of Technology, Lausanne (Switzerland). Dept. of Materials

Solidification of laser-remelted Al-26 wt% Si alloys has revealed a transition from constrained growth to nucleation control of microstructural evolution. Laser scanning velocities between 5 and 8 mm/s resulted in a fibrous eutectic microstructure. For scanning velocities about 8 mm/s, the microstructure consisted of equiaxed, micron-sized silicon crystals surrounded by {alpha}-Al cells that, in turn, were surrounded by fibrous eutectic. An analysis of the transition from growth-controlled to nucleation-controlled microstructure development has been formulated based upon the limiting solidification interface temperature at the transition and a heterogeneous volume nucleation model. With a nucleant distribution and potency that is continuous with increasing undercooling, the model analysis provides a good account of the variation in silicon particle density with scan velocity. The reliability of the model is explored by a sensitivity analysis to establish bounds on unmeasured parameter values and to determine the processing domain of nucleation controlled microstructural evolution.

• OSTI ID: 264090
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 7 Vol. 44; ISSN XZ504Y; ISSN 1359-6454
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CRYSTALS
EUTECTICS
FIBERS
LIQUID METALS
MATHEMATICAL MODELS
MICROSTRUCTURE
RELIABILITY
SILICON
SILICON ALLOYS
SOLIDIFICATION
SURFACES