Study On The Preparation Of Ni-based Binary Intermetallic Compounds Via Solid-liquid Reaction Milling

Reaction ball milling process, which is based on mechanochemical theories, has attracted extensive attention in new materials design and synthesis. Its essence is to induce solid-solid, solid-liquid and solid-gas reactions by ball milling that hardly occur at normal temperature. The available researches have mainly been focused on the reactions in solid-solid and solid-gas systems, while few in solid-liquid systems. And even fewer investigations have been carried out into the mechanochemical reactions between solid and liquid metals. Considering this situation, solid-liquid reaction milling was developed by Prof. Chen on the basis of mechanochemical and thermochemical theories.Ni-Sn, Ni-Sb and Ni-Zn binary alloy systems were investigated by solid-liquid reaction milling, and mechanical alloying of the three systems was carried out under similar conditions. The experimental results were enumerated as follows:1) For the Ni-Sn binary alloy system, Ni balls were selected to mill Sn melt blended with 25mass% Ni powders or not with the ball-to-material mass ratio of 20:1 and the rotation rate of 80rpm. Solid-state Ni₃Sn₂ and Ni₃Sn powders were synthesized after milling the pure Sn melt for 48h at 573 and 1073K, respectively. The addition of 25mass% Ni powders accelerated the reactions and hence the milling time for single-phase Ni₃Sn₂ and Ni₃Sn powders decreased to 36h.2) For the Ni-Sb binary alloy system, Ni balls were selected to mill Sb melt blended with 25mass% Ni powders or not with the ball-to-material mass ratio of 20:1 and the rotation rate of 80rpm. Solid-state NiSb and Ni₅Sb₂ powders were synthesized after milling the pure Sb melt for 24h at 923 and 1023K, respectively. The addition of 25mass% Ni powders accelerated the reactions and hence the milling time for single-phase NiSb and Ni₅Sb₂ powders decreased to 12h.3) For the Ni-Zn binary alloy system, Ni balls were selected to mill Zn melt blended with 25mass% Ni powders or not with the ball-to-material mass ratio of 20:1 and the rotation rate of 80rpm. Solid-state Ni₅Zn₂₁ and NiZn powders were synthesized after milling the pure Zn melt for 24h at 723 and 923K, respectively. The addition of 25mass% Ni powders accelerated the reactions and hence the milling time for single-phase Ni₅Zn₂₁ and NiZn powders decreased to 12h.4) During long time milling of Ni-50mass%Sn, Ni-60mass%Sb and Ni-60mass%Zn blended powders in a planetary milling machine with ball-to-powder mass ratio of 20:1, 15:1 and 12:1 at 250rpm, respectively, no intermetallic phase was examined.The mechanism, process and model of solid-liquid reaction milling for preparing intermetallics were discussed according to the experimental results above with a combination of the effects of liquid metals on solid metals and mechanical force on both solid and liquid metals. Also the differences between solid-liquid reaction milling and mechanical alloying were presented in this thesis.