Misfit paradox on nucleation potency of MgO and MgAl{sub 2}O{sub 4} for Al

Journal Article · Thu Sep 15 04:00:00 EDT 2016 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2016.07.018· OSTI ID:22689611

Zhang, D.; Wang, L. ^[1]; Hari Babu, N. ^[2]; Li, J. G. ^[1]

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1. School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)
2. BCAST, Brunel University London, London UB8 3PH (United Kingdom)

MgO and MgAl{sub 2}O{sub 4} are believed to be effective heterogeneous nuclei for Al based alloys due to their small lattice misfits with Al. However, there is a strong evidence to suggest that liquid Al reacts with MgO and MgAl{sub 2}O{sub 4} phases but the heterogeneous nucleation behavior of such phases is rarely discussed. In order to identify the nucleation mechanism of Al, under the interference of the chemical reaction, the heterogeneous nucleation process is systematically investigated through thermal analysis and high resolution transmission electron microscopy (HRTEM). The observed multi-nucleation interfaces (Al/MgO, Al/MgAl{sub 2}O{sub 4} and Al/Al{sub 2}O{sub 3}) and scattered experimental undercooling data indicate an independent multi-phase nucleation process in these systems. - Highlights: •Theoretical lattice misfit doesn’t always disclose nucleation potency. •The nucleation of liquid can be triggered by multi-nucleation interfaces. •An independent multi-agents nucleation was verified in the study.

• OSTI ID: 22689611
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 119; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
ALUMINIUM BASE ALLOYS
ALUMINIUM OXIDES
CHEMICAL REACTIONS
INTERFACES
LIQUIDS
MAGNESIUM OXIDES
MONOCRYSTALS
NUCLEATION
RESOLUTION
SUBCOOLING
SUBSTRATES
THERMAL ANALYSIS
TRANSMISSION ELECTRON MICROSCOPY