Properties of AlMgB14 hot pressed with additions of ZrB2 and HfB2

Powders of AlMgB14, ZrB2, and HfB2 were combined by high-energy milling to produce AlMgB14+ 60 vol.% ZrB2 and AlMgB14+ 60 vol.% HfB2 composites. The powder constituents were hot pressed at two different temperatures, depending on prior conditioning of the milling vials. SEM and EDS were used to analyze microstructure impurities, and fracture mechanisms. XRD was used to verify proper phase formation and to check for impurity phases. The bulk AlMgB14+ZrB2 and AlMgB14+HfB2 show up to 973% and 98% densification, 222 and 24.5 GPa hardness (measured at 5K-gf), and 4.1 and 3.7 MPa(m)(1/2) toughness, respectively. Also the study of bulk AlMgB14+ZrB2 and AlMgB14+HfB2 composites has shown that these materials exhibit high resistance to erosive and abrasive wear. Multi-hour ASTM erosion tests with Al2O3 abrasive material against composite samples comprised of AlMgB14 (40 vol.%) + ZrB2 (60 vol.%) and AlMgB14 (40 vol.%) +HfB2 (60 vol.%) resulted in erosion rates as low as 4.49 mm(3) of (AlMgB14+ZrB2) wear per kg of erodent and 2.85 mm(3) of (AlMgB14+HfB2) wear per kg of erodent. These values were compared with 14.9 mm(3)/kg for wear-resistant grades of WC-6%Co. (C) 2012 Elsevier B.V. All rights reserved.