Vacuum degassing behavior of Zr-, Ni- and Cu-based metallic glass powders

Abstract The vacuum degassing behavior of Zr 55 Al 10 Ni 5 Cu 30 , Ni 59 Zr 15 Ti 13 Si 3 Sn 2 Nb 7 Al 1 , and Cu 54 Ni 6 Zr 22 Ti 18 (numbers indicate at.%) metallic glass powders has been investigated and compared with that of Al alloy powder. It was found that the alloy composition influenced the gas desorption behavior with heating in vacuo . Zr 55 Al 10 Ni 5 Cu 30 and Ni 59 Zr 15 Ti 13 Si 3 Sn 2 Nb 7 Al 1 metallic glass powders exhibited little H 2 gas desorption from powder surfaces during vacuum degassing. Because Zr in the Zr-based and Ni-based amorphous alloy powders produced a native zirconium oxide layer, the surface of the Zr 55 Al 10 Ni 5 Cu 30 and Ni 59 Zr 15 Ti 13 Si 3 Sn 2 Nb 7 Al 1 amorphous alloys had no influence on adsorbed H 2 O. Cu 54 Ni 6 Zr 22 Ti 18 metallic glass powder was the most affected by atmospheric H 2 O among the metallic glass powders examined in this study. The adsorbed H 2 O and Cu metal may react with each other with the formation of Cu 2 O and liberation of H 2 during vacuum degassing. In order to obtain sound P/M final products with Cu-based P/M alloys, oxygen-free copper powders should be used in well-controlled atmospheres with low H 2 O partial pressures.