New Grain Formation Mechanisms during Powder Bed Fusion
| Autor: | Matthias Markl, Carolin Körner, Alexander M. Rausch, Christoph Breuning, Julian Pistor |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Equiaxed crystals
Technology Materials science Turbine blade nucleation microstructure Nucleation Crystal growth 02 engineering and technology 01 natural sciences Article law.invention Dendrite (crystal) law 0103 physical sciences General Materials Science equiaxed Supercooling 010302 applied physics Microscopy QC120-168.85 Fusion QH201-278.5 Metallurgy crystal growth stray grains grain structure Engineering (General). Civil engineering (General) 021001 nanoscience & nanotechnology Microstructure TK1-9971 Descriptive and experimental mechanics numerical simulation selective electron beam melting Electrical engineering. Electronics. Nuclear engineering ddc:620 TA1-2040 solidification 0210 nano-technology single crystal |
| Zdroj: | Materials Materials, Vol 14, Iss 3324, p 3324 (2021) Volume 14 Issue 12 |
| ISSN: | 1996-1944 |
| Popis: | Tailoring the mechanical properties of parts by influencing the solidification conditions is a key topic of powder bed fusion. Depending on the application, single crystalline, columnar, or equiaxed microstructures are desirable. To produce single crystals or equiaxed microstructures, the control of nucleation is of outstanding importance. Either it should be avoided or provoked. There are also applications, such as turbine blades, where both microstructures at different locations are required. Here, we investigate nucleation at the melt-pool border during the remelting of CMSX-4® samples built using powder bed fusion. We studied the difference between remelting as-built and homogenized microstructures. We identified two new mechanisms that led to grain formation at the beginning of solidification. Both mechanisms involved a change in the solidification microstructure from the former remelted and newly forming material. For the as-built samples, a discrepancy between the former and new dendrite arm spacing led to increased interdentritic undercooling at the beginning of solidification. For the heat-treated samples, the collapse of a planar front led to new grains. To identify these mechanisms, we conducted experimental and numerical investigations. The identification of such mechanisms during powder bed fusion is a fundamental prerequisite to controlling the solidification conditions to produce single crystalline and equiaxed microstructures. |
| Databáze: | OpenAIRE |
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