| In the first part of this thesis, three basic rules that concern the diffusion paths in ternary diffusion couples are discussed. These three rules originate from thermodynamics consideration, mass-balance consideration, and kinetics consideration respectively. These rules were applied to explain the results of 50 wt.% (Pb, In)/Cu ternary diffusion couple experiment presented in the second part of this thesis. These rules were also applied to analyze the synthesis of in-situ SiC/NbSi{dollar}sb2{dollar} composite through solid-state reactions. In both Cu-In-Pb and Nb-Si-C systems, it was demonstrated that considerable insights can be gained by just looking into the thermodynamic and kinetic data of a material system.; In the second part of this thesis, three sets of experiments with increasing degree of complexity were included: (1) liquid In/solid Cu binary diffusion couple experiment, (2) solid In/solid Cu binary diffusion couple experiment, and (3) solid 50 wt.% (Pb, In)/solid Cu ternary diffusion couple experiments. In the first set of experiments, it was found that all stable intermetallic compounds predicted by the Cu-In binary phase diagram showed up. In the second set of experiments, solid In/Cu diffusion couples were annealed at 145, 120, and 100{dollar}spcirc{dollar}C. A new phase, which is metastable at 120{dollar}spcirc{dollar}C and probably metastable at 100{dollar}spcirc{dollar}C, was detected in diffusion couples annealed at 120 and 100{dollar}spcirc{dollar}C. In the third set of experiments, solid 50 wt.% (Pb, In)/Cu diffusion couples were annealed at 170, 145, 120, and 100{dollar}spcirc{dollar}C. The CuIn{dollar}sb2{dollar} observed in binary In/Cu diffusion couples never appeared in any of the diffusion couples, and the only compound found was Cu{dollar}rmsb{lcub}11{rcub}Insb9.{dollar} The growth in all three sets of diffusion couples followed the parabolic kinetics, suggesting the processes were diffusion-controlled. The growth kinetics as well as the underlying mechanism were discussed. The product phase sequences and microstructures were also discussed on the basis of the theoretical analysis presented in the first part of this thesis. |
