Chemical reaction mechanism, microstructural characteristics and mechanical properties of in situ (α-Al 2 O 3 +ZrB 2 )/Al composites
| Autor: | Heguo Zhu, Zhuli Yu, Bo Hua, Jianliang Li, Jiewen Huang, Zonghan Xie |
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| Rok vydání: | 2017 |
| Předmět: |
Materials science
Composite number chemistry.chemical_element 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics Microstructure 01 natural sciences Chemical reaction 0104 chemical sciences Amorphous solid Reaction rate chemistry Aluminium Ultimate tensile strength Particle General Materials Science Composite material 0210 nano-technology |
| Zdroj: | Materials Chemistry and Physics. 196:45-51 |
| ISSN: | 0254-0584 |
| DOI: | 10.1016/j.matchemphys.2017.04.039 |
| Popis: | In-situ (α-Al 2 O 3 +ZrB 2 ) particle reinforced aluminum matrix composites were fabricated from Al-ZrO 2 -B 2 O 3 powder mixtures using chemical reaction method. The chemical reaction mechanism, microstructural characteristics and mechanical properties of the composite were investigated. The chemical reaction process was found to comprise three major steps: step 1: 2Al + B 2 O 3 →2[B]+Al 2 O 3(amorphous) , 2[B]+Al→AlB 2 ,ZrO 2 +2B→Zr(O,B) 2 ; step 2:Al + ZrO 2 →Al 2 O 3(amorphous) +[Zr], [Zr]+Al→Al 3 Zr, [Zr]+Al→AlZr, 3Zr(O,B) 2 +4Al→2Al 2 O 3 +3ZrB 2 ;and step3:Al 3 Zr + AlZr+2AlB 2 →6Al+2ZrB 2 , Al 2 O 3(amorphous) →α-Al 2 O 3 . The transitional phases were found to be AlB 2 and amorphous Al 2 O 3 . Notably, with increasing temperature, amorphous Al 2 O 3 began to crystallize and eventually transformed to more stable α-Al 2 O 3 . The activation energies of the three step reactions were calculated and found to be 641, 330 and 192 kJ/mol, respectively. The reaction rate of the third step was observed to be much higher than that of the second step reaction. Reinforcement particles have a uniform distribution in the aluminum matrix. The α-Al 2 O 3 particles exhibit a size ranging from several hundred nanometers to a few micrometers, while the size of ZrB 2 particles is less than 3 μm. The tensile strength and elongation rate of the composites are determined to be 226 MPa and 4.6%, respectively. |
| Databáze: | OpenAIRE |
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