Cast aluminum alloys with a wide range of spherical α size were prepared utilizing the inclined cooling plate technique. In addition to the change in the α size, the sizes of grain and Si and intermetallic compound particles were significantly reduced and spheroidized by the introduction of semi-solid process. Although almost all the mechanical properties became highest in rheocast material with a α size of 38 μm, the increment was merly 10 % compared to squeeze cast material. Although differences in damage accumulation behavior during tensile loading was quantified by in-situ studies, there did not seem to be discernible effects on fatigue properties. The less than expected improvement was not attributed to differences in grain structure according to the quantitative investigation on microrientation angles between neighboring grains utilizing the SEM-EBSP technique. Relatively modest improvement in comparison to literature seems to be rational, considering that the rheocast process changes only the spatial distribution pattern of the Si particles.

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  TiC is the main component of cermet. It has low specific gravity, and in addition, it has superior hardness and oxidation resistance than WC. However, the TiC particle can not be inserted for gray cast iron in the same way as the WC particle. Thus partial reinforcement of gray cast iron by the TiC particle was attempted in this study. The reinforcement process was examined by planing gray cast iron on TiC powder and heating it, and by buring gray cast iron in TiC powder and heating it. In order to promote reinforcement, nickel powder or carbon steel powder was added. A more or less uniform TiC inserted layer was formed by the addition of over 50 vol % nickel. The matrix near the surface of the inserted layer transformed to a retained austenite by the effects of the nickel.

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  Spheroidal graphite cast iron specimens with various ratios of decarburized layers were made by heat treatment for 86.4-345.6 ks at a temperature range of 973 K to 1373 K. The impact property of the specimens was examined at a temperature range of 233 K to 293 K. The impact value decreased with the increase in the thickness of the decarburized layer for each test temperature. This was suggested to be due to the formation of a pearlite-ring in the decarburized layer. Increasing the thickness of the decarburized layer increased the ratio of the pearlite-ring layer to the decarburized layer. However, the pearlite-ring layer disappeared when the specimen was overdecarburized. Hence, the impact value recovered in the overdecarburized state.
  As a result, the ductile-brittle transition temperature (DBTT) increased with the increase in the thickness of the decarburized layer. The DBTT rose to about 300 K when the specimen was decarburized at 1373 K. On the other hand, the fracture surface after impact test showed brittle fracture even at a room temperature. This tendency was pronounced with the increase in the thickness of the decaruburized layer.
  The impact values obtained were discussed in terms of crack initiation energy and crack propagation energy. These values were sufficiently higher than the standard values for auto parts.

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  High chromium cast irons have poor machinability because of their high hard carbide content. The development of free-cutting high chromium cast irons is therefore desired. In this study machining 2.4 mass % C-15 mass % Cr-1.0 mass % Mo cast irons containing 0 to 0.2 mass % Pb and 0 to 0.4 mass % S were made and the effects of lead and sulphur on hardness, wear resistance and compressive strength of these irons were investigated. The hardness was virtually unaffected by the addition of lead and sulphur. Wear loss of irons with lead was smaller than that of lead free ones under corrosive wear conditions since lead improves the corrosion resistance of iron and suppresses acceleration of wear due to corrosion. Compressive strength of irons containing lead and sulphur decreased slightly compared with that of lead and sulphur free irons. It is evident that machining high chromium cast irons containing lead and sulphur are useful as wear resistant materials.

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  In order to clarify the influence of Fe, Sr and Ca on shrinkage characteristics of Al-Si alloy, investigations were carried out by Tatur mold, thermal analysis and shrinkage measurement. Findings were as follows. 1) Exterior shrinkage increases and interior shrinkage decreases when Ca content increases. 2) Exterior shrinkage decreases and interior shrinkage increases when Fe content increases, in the case of 0.002∼0.006 % Ca. However, Fe content and shrinkage characteristics are not related when Ca is not contained. 3) Exterior shrinkage decreases and interior shrinkage increases when Sr content increases in the case of Sr>0.024 %. But, interior shrinkage decreases and exterior shrinkage increases when Sr content increases in the case of Sr<0.024%. 4) These results can be attributed to the increase of the semi-solidus temperature and decrease of the semi-solid formation time with the existence of the Fe compound or Sr compound.

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  Alumina short fiber preforms with Al₂O₃ binder were fabricated and infiltrated with AC8A aluminum alloy melt by squeeze casting. The effects of fiber volume fraction, temperature, and heat treatment on the tensile strength of the composites were investigated. Aging behavior was not changed by the reinforcement. The Al₂O₃ binder provided a satisfactory interfacial bond between the fiber and the matrix without interfacial reaction or fiber damage. The composites showed peak strength at the fiber volume fraction of 18%, and the strength of the T6 treated composites at 523 K was higher than that of the unreinforced alloy at room temperature. Examination of the fracture surfaces and calculation of the tensile strength using the rule of mixture indicated that the 18% fiber reinforced composite had a strong interfacial bond even at high temperatures.

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