The effect of aluminium on mechanical properties and thermal stability of (Fe, Co, Ni)-Al-B ternary amorphous alloys

Abstract

Amorphous phase formation has been found in a wide range of Fe-Al-B, Co-Al-B and Ni-Al-B ternary systems by a melt-quenching technique. The aluminium content of these amorphous alloys is in the range 0 to 60 at % for Fe- and Co-Al-B systems and 0 to 26 at % for the Ni-Al-B system, but the formation of ductile amorphous phase is limited to less than 20 at % Al. Crystallization temperature and Vickers hardness increase with increasing aluminium and boron content and maximum values are attained at 887 K and 880 diamond pyramid number (DPN). Their fracture strengths are about 2140 to 2680 MPa. The effectiveness of aluminium on the increase in crystallization temperature and hardness is greater in the case of other metal elements such as chromium, manganese, iron, cobalt and nickel, but is less than the metalloid elements such as silicon and boron. This could be reasonably explained by the assumption that aluminium may also possess a weak metalloid character.