Synthesis and Characterization of an Alumina Forming Nanolaminated Boride: MoAlB
2016 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, no 26475Article in journal (Refereed) PublishedText
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 mu Omega m) and - like a metal - drops linearly with decreasing temperatures. It is also a good thermal conductor (35 Wm(-1)K(-1) at 26 degrees C). In the 25-1300 degrees C temperature range, its thermal expansion coefficient is 9.5 x 10(-6) K-1. Preliminary results suggest the compound is stable to at least 1400 degrees 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.
Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP , 2016. Vol. 6, no 26475
IdentifiersURN: urn:nbn:se:liu:diva-129491DOI: 10.1038/srep26475ISI: 000376491700001PubMedID: 27220751OAI: oai:DiVA.org:liu-129491DiVA: diva2:940485
Funding Agencies|Leverhulme Trust; Army Research Office [W911NF-11-1-0525]2016-06-212016-06-202016-08-31