The relationships among strength, toughness and microstructure of the 2091 Al-Li system alloy conducted with thermomechanical processing whose fundamental processes were variously changed, were investigated in order to achieve greater strength and toughness. The warm rolling temperature should be lowered, the warm rolling reduction ratio should be greater, and the best reduction ratio of the cold rolling after the warm rolling is 20% in order to develop the strength and toughsness of the 2091 Al-Li system alloy. The annealing after the warm rolling is no good for strengthening and toughning of the 2091 Al-Li system alloy. The strength and toughness parameter is well related to the subgrain size.

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The strengthening and toughening mechanisms of the 2091 Al-Li system alloy conducted with the thermomechanical processing whose fundamental processes were variously changed were discussed in order to achieve the greater strength and toughness. δ' and S' which are main precipitates and contribute to strengthening of 2091 Al-Li system alloy. δ' is associated with the strengthening of the alloy due to the creation of anti-phase boundary when the dislocation shears δ' while S' is associated with the strengthening of the alloy due to the stress increment brought by dislocations passing δ' by Orowan's mechanism. Toughening of the alloy is associated with the refinement of the subgrain.

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Effects of Mg, Cu and Si on the bake-hardening of Al-2-3 mass%Mg alloys were investigated by the tensile testing, hardness measurments and electron microscopy. The strength in as-solution-treated condition and the bake-hardenability increased with Cu addition up to 0.6%. Although the as-solution-treated strength did not change with Si content, bake-hardenability increased by small addition of 0.1%Si. High bake-hardenability in Al-2-3%Mg alloys with Cu and Si additions was due to the fine and homogeneous GPB zone formation. Cu increased the density of GPB zone in the baked condition at 447K for 1.2ks, whereas Si suppressed dislocation loop formation which would otherwise enhance the inhomogeneous precipitation of the S' phase. In Al-2-3%Mg alloys with small additions of Cu and Si, the hardening during room temperature aging is small, thus these alloys are expected to have a great advantage in the automobile body panel use.

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In this report, the influence of cutting speed on cutting force, surface roughness, tool wear and chip shape of Ti-43.4 at%Al-1.6 at%Mn intermetallics prepared by reactive sintering process using K10 and P10 tools were investigated. K10 tool is suitable for machining of this material than P10 tool. Cutting force is influenced by cutting speed, and it shows almost the same value as that of Ti-6Al-4V alloy if the proper cutting speed is selected. Surface roughness has no relation to cutting speed and TiAl-Mn intermetallics shows almost the same surface roughness as that of Ti-6Al-4V alloy. In the case of using K10 tool, tool wear also has no relation to cutting speed. The chip shape is discontinuous and is not influenced by the cutting speed.

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Five phases of intermetallic compounds such as γ₁, δ, ζ₂, η₂ and θ are formed in a lamellar manner at the Cu/Al interface. As the compounds grow, the copper phase shrinks in a parabolic manner. The parabolic rate constant is described as:
k=11800 exp (-68400/RT).
The hardness of the mixed powder compact increases with sintering time, and the degree of the increment becomes remarkably high as the copper content increases from 5 to 71mass%. The tensile strength of the compact increases with sintering time when the copper content is low, while it decreases when the copper content is high. The area reduction of the compact decreases at the beginning of sintering, but it recovers gradually with time when the copper content is low. The density of the compact decreases with sintering time.

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β-SiC whisker preforms were fabricated by the aid of the γ-Al₂O₃ sintering additive and 6061 matrix composites were successfully produced. The sound preforms are sintered by the heat-treatment at 1000°C for 3 h in a N₂ gas stream. Even in the composite with the γ-Al₂O₃ binder, segregations of Mg and Si are observed in the top and bottom regions. However, no large Si particle is found in the bottom region of the composite. Although the SiO₂ binder composite has low strength both in the top and the bottom regions, the γ-Al₂O₃ composite exhibits high strength in all regions of the ingot.

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Orbital rotary flaring is a process in which a tube-end is flared to fit on a tool-envelope surface made by a relative motion of a tool around the tube. The orbital rotary flaring is to be a hopeful process for small-lot production. However, metal-flow phenomena of the forming are not yet clarified. In this study, metal-flow behaviour of orbital rotary flaring of aluminum tubes is examined in order to clarify the metal-flow mechanism of the forming. The experimental results show that two different types of metal-flow phenomena occur. In the case of half apex angle of tool-envelope surface equals to 90°, flanging mode with inward-flowing takes place following the mushrooming mode. When the half angle is smaller than 90°, flaring mode with inward-flowing mode takes place. In consideration of experimental analysis of strain distributions and their history, the metal-flow mechanism is investigated to explain these two types of metal-flow phenomena and to assess the effect of various process parameters on the metal-flow behaviour.

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