Exploring the Ti-5553 phase transformations utilizing in-situ high-temperature laser-scanning confocal microscopy
Recently, the β metastable Ti-5553 alloy has attracted significant interest owing to the possibility of achieving excellent mechanical properties. In this study, for the first time, the Ti-5553 phase transformations were investigated using high-temperature laser-scanning confocal microscopy (HT-LSCM...
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| Published in: | Materials characterization Vol. 159; p. 110013 |
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| Main Authors: | , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Elsevier Inc
01-01-2020
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Recently, the β metastable Ti-5553 alloy has attracted significant interest owing to the possibility of achieving excellent mechanical properties. In this study, for the first time, the Ti-5553 phase transformations were investigated using high-temperature laser-scanning confocal microscopy (HT-LSCM). During the continuous heating of an aged sample, the α phase dissolution was not clearly visible owing to the remaining grooves of former grain and interphase boundaries. However, the continuous cooling experiments (from the β field) showed that the α phase precipitation started preferentially at grain boundaries. With the increase in cooling rate, the α precipitates became more refined and the supercooling necessary to promote allotriomorphic precipitation increased. At a cooling rate of 100 °C min−1, no α phase was observed in the analyzed field of view. A higher oxygen content was suggested to contribute to the microstructural differences between the free surface and bulk. The volume fraction of the α phase was lower than that obtained on the original surface at cooling rates of 5, 25, and 50 °C min−1, while only minor differences were observed at cooling rates of 100 and 250 °C min−1. The α phase precipitation was analyzed in detail. The HT-LSCM technique can be a useful method for the analyses of solid-state phase transformations in Ti alloys.
•First in-situ phase transformation study of Ti-5553 alloy by confocal microscopy•The high oxygen affinity of Ti demands a highly controlled atmosphere.•Thermal etching grooves persist after phase dissolution, hindering the analysis.•Slower cooling rates favor the precipitation of allotriomorphic α phase.•The allotriomorphic and intragranular α precipitates become more refined as the cooling rate increases. |
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| ISSN: | 1044-5803 1873-4189 |
| DOI: | 10.1016/j.matchar.2019.110013 |