Cost-effective synthesis of AlMgB14–xTiB2

As an alternative to mechanical alloying, high temperature synthesis (HTS) of ultra-hard, super-abrasive AlMgB14 was performed under normal pressure. The reaction mixture consisted of elemental aluminium and boron, whereas magnesium was added in the form of a Mg-precursor which liberates elemental magnesium approximately 400 °C above the melting point of magnesium, in this way reducing its evaporation during heating-up. The composition after the conversion was 95 wt.% of AlMgB14 and 5 wt.% of MgAl2O4. The synthesized AlMgB14 baseline powder, as well as mixtures of AlMgB14 consisting of 30, 50 and 70 wt.% of TiB2, were hot pressed to near theoretical density. The various samples produced were characterized for microstructure and hardness. A micro-hardness of 29.4 GPa in hot pressed AlMgB14 and a maximum Vickers hardness of 30.2 GPa in hot pressed samples of AlMgB14 reinforced with 70 wt.% of TiB2 were achieved.