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Enhanced nanohardness and new insights into texture evolution and phase transformation of TiAl/TiB2 in-situ metal matrix composites prepared via selective laser melting.
- Source :
-
Acta Materialia . Sep2017, Vol. 136, p90-104. 15p. - Publication Year :
- 2017
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Abstract
- TiAl/TiB 2 in-situ metal matrix composites (MMCs) with greatly enhanced nanohardness are prepared via selective laser melting (SLM) for the first time in this study. The effect of TiB 2 reinforcement on the microstructural characteristics, texture evolution and phase transformation of TiAl-based alloy is investigated. The results show that with increasing the TiB 2 content, the average grain size gradually decreases, and the crystallographic orientation transforms from a strong ( 0001 ) direction to ( 10 1 ¯ 1 ) and ( 11 2 ¯ 1 ) directions. Meanwhile, TiB 2 has a great effect on the texture of SLM-processed TiAl/TiB 2 MMCs. With increasing the TiB 2 content, more textured TiAl/TiB 2 MMCs can be produced. The TiAl/TiB 2 MMCs are dominated by α 2 phase and small amounts of γ, B 2 , TiB 2 and TiB phases are also detected. α 2 phase contains the most important texture components of prismatic fiber with { 10 1 ¯ 0 } < 11 2 ¯ 0> orientation, basal fiber with { 0001 } < 11 2 ¯ 0> orientation and pyramidal fiber with { 10 1 ¯ 1 } < 11 2 ¯ 0> and { 11 2 ¯ 2 } < 11 2 ¯ 3 > orientations. The TiB 2 reinforcements are in the forms of the needlelike micro-TiB 2 and irregular nano-TiB 2 particles in the TiAl-based alloy matrix, and the nano-TiB 2 particles are uniformly distributed with the size of 10 nm in length and 3–5 nm in width. The SLM-produced TiAl/TiB 2 MMCs exhibit superior nanohardness of 10.57 ± 0.53 GPa, which is much higher than those of the traditional roll bonding fabricated TiB 2 reinforced TiAl-based alloy. The findings would be a valuable reference for fabricating TiAl/TiB 2 MMCs parts with controlled grain features, crystallographic texture and phase composition, enhanced mechanical properties and complex structures by SLM. [ABSTRACT FROM AUTHOR]
- Subjects :
- *METALLIC composites
*PHASE transitions
*CRYSTALLOGRAPHY
*GRAIN size
*MICROSTRUCTURE
Subjects
Details
- Language :
- English
- ISSN :
- 13596454
- Volume :
- 136
- Database :
- Academic Search Index
- Journal :
- Acta Materialia
- Publication Type :
- Academic Journal
- Accession number :
- 124383900
- Full Text :
- https://doi.org/10.1016/j.actamat.2017.07.003