NMR study and hardness behavior of nanophase Al/Al-oxide consolidated composite

Over the past few years, nanostructured materials (grain sizes 1-100 nm) have generated a lot of interest in the scientific community. This interest has mainly stemmed from the reported superior properties of these materials over conventional ones and their potential for commercial applications.; A variety of techniques including SEM, TEM, PAS, etc. have been used to study nanophase materials. This work reports the study of a nanophase composite material using the non-destructive NMR spectroscopic technique. The composite studied is a nanophase Al/Al-Oxide system with the Al metal in the grains and the Al-Oxide in the grain boundaries.; The production of such a nanoscale Al/Al-Oxide powder is described. Hardness, mass density and electrical conductivity measurements on the pellets formed by the consolidation of this powder at different consolidation pressures is reported. NMR studies of this composite material are reported at room temperature. The design and construction of a high temperature NMR probe is described. Limited high temperature NMR measurements are then described.; Hardness measurements conducted on the samples indicate an increase in hardness with decrease in grain size in accordance with the Hall-Petch relationship. Interestingly, some of the samples were electrically conducting and some non-conducting. An increase in hardness with an insignificant change in mass density was observed in some samples. High temperature NMR results indicate the melting of the Al metal within the oxide at or around the melting point of aluminum (660{dollar}spcirc{dollar}C). X-Ray measurements show no evidence of grain growth with increase in temperature. Both the X-Ray and NMR measurements show a substantial increase in the aluminum-oxide content of the samples after heating. NMR measurements performed on the samples before and after heating show a non-reversible behavior of the samples upon heating with respect to their signal intensity. Hardness tests performed on the samples after heating them indicate an increase in hardness by as much as a factor of five as compared to the hardness of the unheated samples.; In conclusion, the experiments have successfully demonstrated the synthesis of a unique nanophase low density, high strength composite material capable of retaining its superior properties even above the melting point of aluminum.