Synthesis and Characterization of an Alumina Forming Nanolaminated Boride: MoAlB
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Published version
Author(s)
Type
Journal Article
Abstract
The ‘MAlB’ phases are nanolaminated, ternary transition metal borides that consist of a transition metal boride sublattice interleaved by monolayers or bilayers of pure aluminum. However, their synthesis and properties remain largely unexplored. Herein, we synthesized dense, predominantly single-phase samples of one such compound, MoAlB, using a reactive hot pressing method. High-resolution scanning transmission electron microscopy confirmed the presence of two Al layers in between a Mo-B sublattice. Unique among the transition metal borides, MoAlB forms a dense, mostly amorphous, alumina scale when heated in air. Like other alumina formers, the oxidation kinetics follow a cubic time-dependence. At room temperature, its resistivity is low (0.36–0.49 μΩm) and – like a metal – drops linearly with decreasing temperatures. It is also a good thermal conductor (35 Wm−1K−1 at 26 °C). In the 25–1300 °C temperature range, its thermal expansion coefficient is 9.5 × 10−6 K−1. Preliminary results suggest the compound is stable to at least 1400 °C in inert atmospheres. Moderately low Vickers hardness values of 10.6 ± 0.3 GPa, compared to other transition metal borides, and ultimate compressive strengths up to 1940 ± 103 MPa were measured at room temperature. These results are encouraging and warrant further study of this compound for potential use at high temperatures.
Date Issued
2016-05-25
Date Acceptance
2016-04-29
Citation
Scientific Reports, 2016, 6
ISSN
2045-2322
Publisher
Nature Publishing Group
Journal / Book Title
Scientific Reports
Volume
6
Copyright Statement
This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
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Sponsor
Engineering & Physical Science Research Council (E
Grant Number
J13614 (EP/K008749/1)
Subjects
Science & Technology
Multidisciplinary Sciences
Science & Technology - Other Topics
MECHANICAL-PROPERTIES
HYDROGEN EVOLUTION
TEMPERATURE-RANGE
CRYSTAL STRUCTURE
MAX PHASES
OXIDATION
SILICIDES
CHEMISTRY
ELEMENTS
BATTERY
Publication Status
Published
Article Number
26475