Al-Cr-Fe quasicrystals and their applications as reinforcements in the Ti based metal matrix composites
In this study, the microstructural evolution and phase transformations of gas atomized Al-Cr-Fe powders during annealing process, spark plasma sintering (SPS) of Al-Cr-Fe powders and SPS of Ti/Al-Cr-Fe metal matrix composites (MMCs) were investigated. There are four phases identified in the annealed...
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| Other Authors: | |
| Format: | Thesis |
| Language: | English |
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2015
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| Online Access: | https://hdl.handle.net/10356/65536 |
| _version_ | 1826126249009872896 |
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| author | Li, Ruitao |
| author2 | Dong Zhili |
| author_facet | Dong Zhili Li, Ruitao |
| author_sort | Li, Ruitao |
| collection | NTU |
| description | In this study, the microstructural evolution and phase transformations of gas atomized Al-Cr-Fe powders during annealing process, spark plasma sintering (SPS) of Al-Cr-Fe powders and SPS of Ti/Al-Cr-Fe metal matrix composites (MMCs) were investigated. There are four phases identified in the annealed Al-Cr-Fe powders: icosahedral Al-Cr-Fe, decagonal Al-Cr-Fe, Al9(Cr,Fe)4 and Al8(Cr,Fe)5, with decagonal Al-Cr-Fe forming in the annealing process. Icosahedral Al-Cr-Fe is face-centered. Decagonal Al-Cr-Fe has a periodicity of about 1.2 nm along its periodic axis and it can be well superimposed by Penrose tilings. Al-Cr-Fe powders have been successfully sintered using SPS. With the rise of the sintering temperature from 650 ˚C to 800 ˚C, the relative density of the pellets increases from 70% to 99% and their microhardness increases from Hv 400 to Hv 810. The dominant densification mechanism of Al-Cr-Fe powders in the SPS process is powder rearrangement and dislocation motion. The SPS process promotes the formation of decagonal Al-Cr-Fe. Ti/Al-Cr-Fe MMCs with Ti as matrix and Al-Cr-Fe quasicrystals as reinforcements have been successfully prepared using high pressure SPS. Interfacial layer forms between Ti and Al-Cr-Fe during the sintering process. This layer mainly consists of Al3Ti and AlTi. With the increase of sintering pressure from 50 MPa to 300 MPa, the compositional changes of Al-Cr-Fe are reduced. The addition of Al-Cr-Fe particles to Ti matrix significantly improves the hardness and reduces the wear rate.
This study shows for the first time that Al-Cr-Fe quasicrystals can be sintered using SPS and SPS process can promote the formation of decagonal Al-Cr-Fe and the increased sintering pressure leads to reduced compositional changes of Al-Cr-Fe reinforcements in the Ti based MMCs prepared using SPS. |
| first_indexed | 2024-10-01T06:49:34Z |
| format | Thesis |
| id | ntu-10356/65536 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T06:49:34Z |
| publishDate | 2015 |
| record_format | dspace |
| spelling | ntu-10356/655362023-03-11T17:43:40Z Al-Cr-Fe quasicrystals and their applications as reinforcements in the Ti based metal matrix composites Li, Ruitao Dong Zhili Khor Khiam Aik School of Mechanical and Aerospace Engineering DRNTU::Engineering::Materials::Metallic materials::Alloys In this study, the microstructural evolution and phase transformations of gas atomized Al-Cr-Fe powders during annealing process, spark plasma sintering (SPS) of Al-Cr-Fe powders and SPS of Ti/Al-Cr-Fe metal matrix composites (MMCs) were investigated. There are four phases identified in the annealed Al-Cr-Fe powders: icosahedral Al-Cr-Fe, decagonal Al-Cr-Fe, Al9(Cr,Fe)4 and Al8(Cr,Fe)5, with decagonal Al-Cr-Fe forming in the annealing process. Icosahedral Al-Cr-Fe is face-centered. Decagonal Al-Cr-Fe has a periodicity of about 1.2 nm along its periodic axis and it can be well superimposed by Penrose tilings. Al-Cr-Fe powders have been successfully sintered using SPS. With the rise of the sintering temperature from 650 ˚C to 800 ˚C, the relative density of the pellets increases from 70% to 99% and their microhardness increases from Hv 400 to Hv 810. The dominant densification mechanism of Al-Cr-Fe powders in the SPS process is powder rearrangement and dislocation motion. The SPS process promotes the formation of decagonal Al-Cr-Fe. Ti/Al-Cr-Fe MMCs with Ti as matrix and Al-Cr-Fe quasicrystals as reinforcements have been successfully prepared using high pressure SPS. Interfacial layer forms between Ti and Al-Cr-Fe during the sintering process. This layer mainly consists of Al3Ti and AlTi. With the increase of sintering pressure from 50 MPa to 300 MPa, the compositional changes of Al-Cr-Fe are reduced. The addition of Al-Cr-Fe particles to Ti matrix significantly improves the hardness and reduces the wear rate. This study shows for the first time that Al-Cr-Fe quasicrystals can be sintered using SPS and SPS process can promote the formation of decagonal Al-Cr-Fe and the increased sintering pressure leads to reduced compositional changes of Al-Cr-Fe reinforcements in the Ti based MMCs prepared using SPS. DOCTOR OF PHILOSOPHY (MAE) 2015-10-22T06:17:37Z 2015-10-22T06:17:37Z 2015 2015 Thesis Li, R. (2015). Al-Cr-Fe quasicrystals and their applications as reinforcements in the Ti based metal matrix composites. Doctoral thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/65536 10.32657/10356/65536 en 155 p. application/pdf |
| spellingShingle | DRNTU::Engineering::Materials::Metallic materials::Alloys Li, Ruitao Al-Cr-Fe quasicrystals and their applications as reinforcements in the Ti based metal matrix composites |
| title | Al-Cr-Fe quasicrystals and their applications as reinforcements in the Ti based metal matrix composites |
| title_full | Al-Cr-Fe quasicrystals and their applications as reinforcements in the Ti based metal matrix composites |
| title_fullStr | Al-Cr-Fe quasicrystals and their applications as reinforcements in the Ti based metal matrix composites |
| title_full_unstemmed | Al-Cr-Fe quasicrystals and their applications as reinforcements in the Ti based metal matrix composites |
| title_short | Al-Cr-Fe quasicrystals and their applications as reinforcements in the Ti based metal matrix composites |
| title_sort | al cr fe quasicrystals and their applications as reinforcements in the ti based metal matrix composites |
| topic | DRNTU::Engineering::Materials::Metallic materials::Alloys |
| url | https://hdl.handle.net/10356/65536 |
| work_keys_str_mv | AT liruitao alcrfequasicrystalsandtheirapplicationsasreinforcementsinthetibasedmetalmatrixcomposites |