Hierarchical microstructure of a titanium alloy fabricated by electron beam selective melting
| Autor: | Jixin Yang, Chao Guo, Yiqiang Chen, Baokun Liu, Yongjiang Huang, Zhiliang Ning, Jianfei Sun |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Materials science
Fabrication Polymers and Plastics Mechanical Engineering Alloy Metals and Alloys Titanium alloy 02 engineering and technology engineering.material 010402 general chemistry 021001 nanoscience & nanotechnology Thermal conduction Microstructure 01 natural sciences Indentation hardness 0104 chemical sciences Mechanics of Materials Phase (matter) Martensite Materials Chemistry Ceramics and Composites engineering Composite material 0210 nano-technology |
| Zdroj: | Journal of Materials Science & Technology. 42:1-9 |
| ISSN: | 1005-0302 |
| DOI: | 10.1016/j.jmst.2019.09.015 |
| Popis: | Here, a near alpha-type Ti6.5Al2Zr1Mo1V alloy has been fabricated by electron beam selective melting (EBSM). Near-equiaxed grains existed in the first few layers, whereas elongated columnar prior β grains almost parallel to the building direction formed in the subsequent built layers. Interspacing of β phase gradually decreased as the build height increased. Martensite α′ with twins and dislocations emerged and microhardness value reached the maximum in the top region, whereas only α/β phase appeared in other regions in the EBSMed sample. Multiple phase transformations can be observed with the change of peak temperatures during each thermal cycle. With a sufficient dwell time, martensite α′ in the middle and bottom regions in-situ decomposed into α + β and coarsened by the heat conduction from the subsequent layers. Fine β precipitates nucleated heterogeneously inside α′ plates and at plate-plate interfaces during the subsequent EBSM process. Considering the phase transformation during the heating process and the cooling process, the existence time of different phases was combined with cycle heating and cooling to clarify the dynamic evolution of microstructure under complex thermal history of EBSM, favoring the fabrication of high-performance titanium alloy components. |
| Databáze: | OpenAIRE |
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