For producing the particle dispersed Metal Matrix Compsite (MMC), we tried to cristallize the SiC particles in molten metal. Fe-25%Si and Ni-25%Si were selected. These alloys were melted in pure-graphite crucible in CO or Ar atmosphere at 1,500°C and hold up to 20h.
  The main results are follows;
  1) SiC crystallize in Fe-Si-C system and Ni-Si-C system. In the former, the rate of SiC crystallization is higher and more crystallized SiC are obtained.
  2) In CO atmosphere SiC crystallize as particle, and in Ar as group on crucible wall.
  3) The difference of SiC morphology is caused by existence of SiO₂ film at molten metal-crucible interface.

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  High-strength high-toughness austempered spheroidal graphite cast iron has been put into practical use, and begun to be applied to parts requiring high-fatigue strength as an alternate material for forgings. The design of strength-requiring parts, on the other hand, has been changing to one using the parameters such as stress intensity factors and fatigue crack growth rates based on the fracture mechanics.
  However, the effect of graphite on the fatigue behavior of spheroidal graphite cast iron, especially on the fatigue crack growth rate are not clarified yet. Accordingly, a series of fatigue tests were carried out for 4 kinds of ferrite and pearlite base substrate spheroidal graphite cast iron with different graphite particle size and for ferrite base substrate SS 41 and pearlite base substrate SK 5 by changing stress ratios in three stages-i. e. 0.1, 0.3, and 0.5.
  The testing was performed in the second region of fatigue in which fatigue cracks grow stably. The relation between the fatigue crack growth rate (da/dN) and stress intensity factor range (ΔK) were examined and arranged by using the effective stress intensity facter range (ΔKeff) proposed by Elber. The dimensions of the plastic area generated at the ends of cracks were also measured to study the effects of the graphite particle size and substrate structure on the fatigue crack growth rate of spheroidal graphite cast iron.
  The results indicated that in the stress ratio ranging from 0.1 to 0.5, the effect of stress ratio in the case of spheroidal graphite cast iron could be explained by applying the concept of ΔKeff. It was also clarified that the crack growth rate of spheroidal graphite cast iron depended on the graphite particle size and the size of the plastic deformation area formed at the end of a crack namely, with the value of ΔK where the dimension of plastic area is equal to the particle size of graphite being the boundary, graphite reduces the crack growth rate like the key hole for stress relieving in the low ΔK region in which the plastic area is smaller than the graphite particle size, whereas graphite enhances brittle fracture to increase the crack growth rate in the high ΔK region in which the plastic area is greater than the graphite particle size.

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  AC4CH aluminum alloys were cast with a sand mold, a permanent mold and a permanent mold cooled by water. From each ingot, test pieces were prepared, and provided for the tensile test, the fatigue test, and the elastic-plastic fracture toughness test. The threshold stress intensity for the fatigue crack growth was independent on the cast structure and the tensile properties, and took the value of 3.0MPa·m^1/2. There was no relations between the elasto-plastic fracture toughness and the stress intensity at final fatigue failure. The both increased with the increase of the grain size of a phase and eutectic Si. The elasto-plastic fracture toughness increased with the 0.2% proof stress, the ultimate tensile strength and the elongation. The stress intensity at final failure had no relations with the tensile properties, except the elongation.

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  Contuitive equations for mechanical properties of cast aluminum AC4C and ADC12 alloys were investigated in the temperature 360°C to eutectic temperature and the strain rate of 5×10^-4 to 10^-1 per second to obtain fundamental data for deformation behavior of castings. Flow stress was represented in the quadratic form of strain, strain rate and temperature of above mentioned range by the multi-regression method. Tensile strength decreased with increaing in temperature and decreasing in strain rate. Ductility droped abruptly near the eutectic temperature.

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