AlM2B2 (M  =  Cr, Mn, Fe, Co, Ni): a group of nanolaminated materials

Combining theory with experiments, we study the phase stability, elastic properties, electronic structure and hardness of layered ternary borides AlCr2B2, AlMn2B2, AlFe2B2, AlCo2B2, and AlNi2B2. We find that the first three borides of this series are stable phases, while AlCo2B2 and AlNi2B2 are meta...

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Bibliographic Details
Published in:Journal of physics. Condensed matter 2017-03, Vol.29 (15), p.155402-155402
Main Authors: Kádas, K, Iu an, D, Hellsvik, J, Cedervall, J, Berastegui, P, Sahlberg, M, Jansson, U, Eriksson, O
Format: Article
Language:English
Subjects:
elastic constants
hardness
nanolaminated ternary borides
phase stability
scanning electron microscopy
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Summary:Combining theory with experiments, we study the phase stability, elastic properties, electronic structure and hardness of layered ternary borides AlCr2B2, AlMn2B2, AlFe2B2, AlCo2B2, and AlNi2B2. We find that the first three borides of this series are stable phases, while AlCo2B2 and AlNi2B2 are metastable. We show that the elasticity increases in the boride series, and predict that AlCr2B2, AlMn2B2, and AlFe2B2 are more brittle, while AlCo2B2 and AlNi2B2 are more ductile. We propose that the elasticity of AlFe2B2 can be improved by alloying it with cobalt or nickel, or a combination of them. We present evidence that these ternary borides represent nanolaminated systems. Based on SEM measurements, we demonstrate that they exhibit the delamination phenomena, which leads to a reduced hardness compared to transition metal mono- and diborides. We discuss the background of delamination by analyzing chemical bonding and theoretical work of separation in these borides.
ISSN:0953-8984
1361-648X
1361-648X
DOI:10.1088/1361-648X/aa602a