Stabilization of HfB12 in Y1-xHfxB12 under Ambient Pressure.
Alloys of metal dodecaborides-YB12 with HfB12-were prepared via arc-melting in order to stabilize the metastable HfB12 high-pressure phase under ambient pressure. Previously, HfB12 had been synthesized only under high-pressure (6.5 GPa). Powder X-ray diffraction (PXRD) and energy-dispersive X-ray spectroscopy (EDS) were used to confirm the purity and phase composition of the prepared samples. The solubility limit for HfB12 in Y1-xHfxB12 (cubic UB12 structure type) was determined to be ∼35 at. % Hf by PXRD and EDS analysis. The value of the cubic unit cell parameter (a) changed from 7.505 Å (pure YB12) to 7.454 Å across the solid solution range. Vickers hardness increased from 40.9 ± 1.6 GPa for pure YB12 to 45.0 ± 1.9 GPa under an applied load of 0.49 N for the Y1-xHfxB12 solid solution composition with ∼28 at. % Hf, suggesting both solid solution hardening and extrinsic hardening due to the formation of secondary phases of hafnium.
Department of Chemistry and Biochemistry, ‡Department of Materials Science and Engineering, and §California NanoSystems Institute (CNSI), University of California, Los Angeles (UCLA) , Los Angeles, California 90095, United States.
Georgiy
G
Akopov
Department of Chemistry and Biochemistry, ‡Department of Materials Science and Engineering, and §California NanoSystems Institute (CNSI), University of California, Los Angeles (UCLA) , Los Angeles, California 90095, United States.
Michael T
MT
Yeung
Department of Chemistry and Biochemistry, ‡Department of Materials Science and Engineering, and §California NanoSystems Institute (CNSI), University of California, Los Angeles (UCLA) , Los Angeles, California 90095, United States.
Christopher L
CL
Turner
Department of Chemistry and Biochemistry, ‡Department of Materials Science and Engineering, and §California NanoSystems Institute (CNSI), University of California, Los Angeles (UCLA) , Los Angeles, California 90095, United States.
Rebecca L
RL
Li
Department of Chemistry and Biochemistry, ‡Department of Materials Science and Engineering, and §California NanoSystems Institute (CNSI), University of California, Los Angeles (UCLA) , Los Angeles, California 90095, United States.
Richard B
RB
Kaner