Metal films (i.e., Ti, Al and SUH310S) were prepared in a magnetron sputtering apparatus, and their cross-sectional structures were investigated using scanning electron microscopy. The apparatus used consisted of a cylindrical metal target which was electrically grounded, and two anode rings attached to the top and to the bottom of the target. A wire was placed along the center-line of the cylindrical target to provide a substrate. When the electrical potential of the substrate was varied, the metal-film formation rate depended on both the discharge voltage and the electrical potential of the substrate. As we made the magnetic field stronger, the plasma which appeared near the target collected on the plasma wall surface and thereby decreased the bias current. The bias current on the conducting wire was different from that for cation collection. The bias current decreased because the collection of cations decreased when we increased the magnetic-coil current. When the substrate was electrically isolated, the films deposited showed a slightly coarse columnar structure with thin voids between adjacent columns. In contrast, in the case of the grounded substrate, the deposited film did not show any clear columns but instead, showed a densely-packed granular structure. No peeling region was observed between the film and substrate, indicating good adhesion.

The mechanical properties and microstructures of aluminum-matrix composites fabricated by the dispersion of fine alumina particles less than 20μm in size into 6061 aluminum alloys are investigated in this study. In the as-quenched state, the yield stress of the composite is 40~85 MPa higher than that of the 6061 alloy. This difference is attributed to the high density of dislocations within the matrix introduced due to the difference in the thermal expansion coefficients between the matrix and the reinforcement. The difference in the yield stress between the composite and the 6061 alloy decreases with the aging time and the age-hardening curves of both materials show a similar trend. At room temperature, the strain-hardening rate of the composite is higher than that of the 6061 alloy, most likely because the distribution of reinforcements enhances the dislocation density during deformation. Both the yield stress and the strain-hardening rate of the T6-treated composite decrease as the testing temperature increases, and the rate of decrease is faster in the composite than in the 6061 alloy. Under creep conditions, the stress exponents of the T6-treated composite vary from 8.3 at 473 K to 4.8 at 623 K. These exponents are larger than those of the 6061 matrix alloy.

The mechanical behavior and microstructural evolution during high temperature tensile deformation of recrystallizedNi3Al polycrystals doped with boron were investigated as functions of initial grain size, tensile strain rate and temperature. Inorder to obtain more precise information on the deformation mechanism, tensile specimens were rapidly quenched immediatelyafter deformation at a cooling rate of more than 2000Ks−1, and were then observed by transmission electron microscopy (TEM).Mechanical tests in the range of 923K to 1012K were carried out in a vacuum of less than 3×10−4 Pa using an Instron-typemachine with various but constant cross head speeds corresponding to the initial strain rates from 1.0×10−4 to 3.1×10−5s−1.After heating to deformation temperature, the specimen was kept for more than 1.8ks before testing. The following results wereobtained: (1) Flow behavior was affected by initial strain size; with decreasing initial grain size, the level of a stress peak inthe true stress-true strain curve decreased, the steady state region was enlarged and elongation increased. (2) On the basis ofTEM observation of rapidly quenched specimens, it was confirmed that dynamic recrystallization certainly occurred ondeformation of fine-grained (3.3µm) and intermediate-grained (5.0µm) specimens at an initial strain rate of 3.1×10−5s−1 andat 973K. (3) There were some dislocation-free grains among the new recrystallized grains. The obtained results suggest thatboth dynamic recrystallization and grain boundary sliding are operative during high temperature deformation.