Effects of melt-pool geometry on crystal growth and microstructure development in laser surface-melted superalloy single crystals
- Department of Materials Science and Engineering, Lehigh University, 5 E. Packer Avenue, Bethlehem, PA 18015 (United States)
The effects of melt-pool geometrical parameters on crystal growth and microstructure development during laser surface melting of single-crystal alloys were studied by means of mathematical modeling and experiments. A mathematical model was developed for the three-dimensional (3-D) melt-pool geometry and single-crystalline melt-pool solidification in laser surface melting. The 3-D melt-pool geometry corresponding to the solidification interface is described by four geometrical parameters (w, l, h, {alpha}). The model was used to study the effects of variations in the geometrical parameters on crystal growth and microstructure development in the melt pool. Laser surface melting experiments with single-crystal nickel-base superalloys were conducted to verify the computational results of microstructure development in the melt pool. Results indicate that the melt-pool geometrical parameters have profound influences on the dendrite growth velocity and growth pattern in the melt pool. For the (0 0 1)/[1 0 0] substrate orientation, variations in l/w and {alpha} can influence both the number and the relative sizes of growth regions while the variation in h/w can only influence the relative sizes of the growth regions. Unidirectional dendrite growth along the [0 0 1] crystallographic direction can be achieved for an {alpha} value of 45 deg or below. The maximum ratio of dendrite-growth velocity to the beam velocity in the melt pool is related to {alpha} and l/w. Experimental microstructure observations agreed well with the computational results. These findings show that the desired dendrite growth velocity and microstructure can be obtained through proper control of the 3-D melt-pool geometry.
- OSTI ID:
- 20634777
- Journal Information:
- Acta Materialia, Vol. 52, Issue 16; Other Information: DOI: 10.1016/j.actamat.2004.06.041; PII: S1359-6454(04)00390-8; Copyright (c) 2004 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 1359-6454
- Country of Publication:
- United States
- Language:
- English
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