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Formation of nano-scale ω-phase in arc-melted micron-scale dendrite reinforced Zr73.5Nb9Cu7Ni1Al9.5 ultrafine composite during heat treatment
- Source :
-
Intermetallics . Apr2008, Vol. 16 Issue 4, p538-543. 6p. - Publication Year :
- 2008
-
Abstract
- Abstract: An arc-melted Zr73.5Nb9Cu7Ni1Al9.5 alloy consists of dendritic body-centered cubic solid solution and a mixture of ultrafine body-centered tetragonal Zr2Cu-type and hexagonal close-packed MgZn2-type phases in the ultrafine matrix. This composite exhibits two exothermic reactions upon heating to 973K with a heating rate of 40K/min. After the first exothermic reaction nano-scale ω-phase particles have formed in the β-phase dendrites indicating a decomposition of the supersaturated solid solution upon heating. At the early stage during the decomposition of the β-phase the ω-phase is coherent with the parent phase without clear structural differences. However, semicoherency between the β- and the nano-scale ω-phase regions was observed during the growth of the ω-phase. This structural semicoherency causes nano-scale twinning in the β-phase dendrites around the ordered ω-phase in order to release the mismatch energy at the interfaces between the ordered ω- and β-phases. [Copyright &y& Elsevier]
- Subjects :
- *DENDRITIC crystals
*COPPER
*COMPOSITE materials
*CARBON composites
*HEAT
Subjects
Details
- Language :
- English
- ISSN :
- 09669795
- Volume :
- 16
- Issue :
- 4
- Database :
- Academic Search Index
- Journal :
- Intermetallics
- Publication Type :
- Academic Journal
- Accession number :
- 31400102
- Full Text :
- https://doi.org/10.1016/j.intermet.2007.12.014