Effects of active filler metal composition on the shear strength and reaction products of Al₂O₃-Hovar joints were studied. The variation of microstructures of reaction products formed at the interface between Al₂O₃ and active filler metal was investigated by scanning electron microscopy, auger electron microscopy.
Increasing of Cu component in the active filler metal (Ag-35mass%Cu-2mass%Ti) improves shear strength about 210-240MPa of Al₂O₃-Kovar joints brazed at 1123K for 900s and thickness change of active filler metal do not influenced on the shear strength of Al₂O₃-Kovar joint.Reaction layer Ti_2.9 (Cu, Al) _1.9O_1.3 were formed in the interface between active filler metal and Al₂O₃. High shear strengh of Al₂O₃-Kovar joints are attributed to the formation of these reaction layers.

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For a further understanding an effect of impurities on mechanical property of α brass, tensile test was conducted at elevated temperatures up to 803K under a strain rate of 6.7 x 10^-4 s^-1 using three kinds of Cu-30mass%Zn containing some different impurities with different grain sizes. The coarse-grained specimens show a poor ductility at intermediate temperature range, while fine-grained specimens show an excellent ductility. However, these tendencies strongly depend on contents of the impurities. In particular the alloy containing Sn and Fe tends to show poor ductility.
Elongation to fracture was discussed concerning the formation of recrystalized structure with fine grains due to dynamic recrystalization and due to the effect of impurities on the dynamic recrystalization.

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In order to automate the scooping task of piled fragment rocks by using the wheel loader or Load-Haul-Dump, it is desirable that the resistive forces acting on the bucket are obtained before the scooping task is performed. However, the resistive forces acting on the bucket are not made clear yet because the changes in shape of the rock pile due to the movement of the bucket are unknown. In this paper, the changes in shape of the rock pile due to the movement ofthe bucket were simulated by use of DEM (Distinct Element Method), and the resistive forces acting on the bucket were calculated. Through the numerical simulation, the changes in shape of the rock pile due to the movement of the bucket were made clear. Furthermore, by comparing the experimental results and simulated results, it was found that the agreement was almost satisfactory. Therefore, it was confirmed that DEM simulation was useful to estimate the resistive forces acting on the bucket.

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It was mainly studied using laboratory hot rolling mill that edge cracks of hot rolling plates of CDA Copper Alloy C64740 (Cu-Sn-Ni-Si-Zn system copper alloy) occur during hot rolling at high temperatures from 1073 to 1173K. One cause of the cracks results from sulfur contamination, which is solvable to reduce sulfur or generate the sulfides of MnS and MgS by adding manganese and magnesium in melting and casting, in short, by the scavenging effect. Another comes from silicon increase in the alloy, which is basically important, strengthens the matrix as compared with the grain boundary at the high temperatures, and brings about intergranular fracture due to the concentration of hot rolling stress to the grain boundary.
An experimental method of 1 pass·Ereduction is very effective to evaluate the shortness of the alloy at the high temperatures whose results are consistent to the commercial production's.

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Using the first-and second-derivatives of the effective interatomic potential in the microscopic electronic theory, the interatomic force constants are calculated for practical material Al with low density and for alkali metal K with high density. The interatomic force constants so obtained are in good agreement with those derived from fitting the experimental phonon spectra and give a set of important data for the binding forces of solids. Dynamical elastic constants are also calculated using the long-wave phonon method and are also compared with observed data from ultrasonic pulse method. The compressibility problem, proposed by Brovman and Kagan, is that the lattice dynamical method in terms of second-order perturbation based on the pseudopotential does not give the self-consistent results for calculation of the elastic constants accompanied by a volume change. This problem is studied quantitatively and is shown to be important for Al and K. Consecluently, the obtained data of the elastic constants C11, C12 and bulk modulus B related to volume change are in good agreement with the observed data in spite of introducing no adjustable parameter. Then, in quasi-harmonic approximation considering temperatureand pressure-dependence of the lattice constant, the temperature and pressure effect on the elastic constants are calculated. The obtained data are consistent with the qualitative tendency of observed data and are useful in studying the mechanical and thermal properties of theses materials.

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The carburizing time is expected to be short at high temperatures, where grains of the dual-phase steel are fine and hardly grow. If it can be used for the elevated temperature case hardening steel, the processing time might become short by reducing carburizing time and by skipping the first step quenching for grain refinement of the un-carburized core. In the present study, the applicability of the dual-phase steel for the elevated temperature case hardening steel has been investigated.
The 2.0 mass% Si-(0.01-0.08) mass% C-(0.1 mass% V, 0.05 mass% Nb and 0.05 mass% Ti) steel were carburized at 1323 K for 10.8 ks, quenched from various temperatures and then tempered at 423 K. The microstructural observation, hardness measurement and tensile test of the core were carried out. When the microstructure was controlled to be dual-phase with α+γ at the carburizing temperature, the grains were fine and no grain growth was observed during the carburizing process. Therefore, the first step quenching for grain refinement might be skipped. The core showed the excellent strength-ductility combination compared with the conventional case hardening steel. The distribution of hardness in the carburized layer showed a gentle gradient due to the elevated temperature carburizing. The carburizing time was reduced to be 1/ 3 compared with the conventional carburizing. The grains in the carburized layer were also refined by additions of V, Nb and Ti.

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Unidirectional solidification of Fe-25% Cr-3.5% C eutectic high chromium white cast irons was conducted under a solidification rate range from 1.3×10^-3 mm/s to 1.3×10^-1 mm/s to clarify the deformation behavior of the irons at elevated temperatures. The alloy specimens were processed in the parallel and vertical directions to the solidification direction, and a compression test was done under a strain rate range from 2.5×10^-4 to 1.7×10^-2 at various temperatu res up to 1073 K. The relation between the microstructure and high temperature strength was studied. The strength depended on the morphology of eutectic cells and the orientation of primary carbides. The maximum compressive strength of the parallel direction to the solidification direction was larger than that of the vertical direction within the whole temperature ranges. The strain rate sensitivity exponent showed larger value in the vertical direction than in the parallel direction. These results suggest that the strength of the parallel direction is mainly supported by the elongated primary carbide phases, while the strength of vertical direction is supported by the iron matrix and strongly depend on the deformation behavior of the iron matrix. The rule of mixtures was used for analysis of the experimental results described above.

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For a further understanding of high temperature tensile-deformation behavior of a Cu-30 mass% Zn binary alloy depending on the strain rate, the structure and the stress-strain curves were investigated in detail, at 673 K, using a salt bath (NaNO₃: KNO₃=1: 1) under a strain rate range from 3.3×10^-5 to 2.0×10^-1s^-1. Specimens with three grain sizes ranging from 0.012 to 0.045 mm diameter were used. When dynamic recrystallization occurred at 673 K, the stress decreased. After the initial grain shape changed to dynamic recrystallization, the stress-strain curves showed a steady state, and did not depend on the occurrence or the growth of voids. The peak strain, which is the strain at maximum stress, was hardly dependent on the size of the initial grain, but dependent on the strain rate. Thus, the peak strain increases with strain rate. At this time, the dynamic recrystallization form is a bulging mechanism and simultaneously, a nucleation mechanism. This occurrence happened at about 20-30% peak strain. Initial void formation depended on the strain rate. And the strain appearing void increased with increased in strain rate. Cavities of fractured specimens showed 4 different shapes in three dimensions which corresponded to initial grain size and strain rate. Fractured elongation reveals a tendency to become smaller, when cavities start to combine and grow into a 45 degree angle in relate to the tensile direction. On the other hand, the specimens exhibit large elongation, when cavities combine and grow in the tensile direction.

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In the previous paper, we reported the low alloyed dual-phase steel could be used for elevated temperature case hardening steels without the first step quenching from microstructure observations. In the present work, mechanical properties and optimum quenching temperature of the dual-phase steels were investigated for practical case hardening applications.
The microstructural and mechanical properties of the 0.05 mass% C-2.0 mass % Si-(0.05 mass% Nb and 0.05 mass% Ti) steels carburized at 1323K for 10.8ks, quenched from 1123K-1223K and then tempered at 423K were studied. The maximum tensile and fatigue strength of the 2.0 mass% Si steel and the 2.0 mass% Si-(0.05 mass% Nb and 0.05 mass% Ti) steel were obtained after quenching from 1123K and 1223K, respectively. These properties were much higher than those of the conventional case hardening steel obtained by two step quenching. The wear resistance was not affected by quenching temperature and was much superior in the regions of higher and lower sliding speed compared with the carbon tool steel (SK 3). Skipping the first step quenching and carburizing at elevated temperatures make the processing time shorter and energy consumption to fab-ricate materials smaller. Thus, the dual-phase steel is considered to have a potential for practical use for the elevated temperature case hardening steel.

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