Hypoeutectic Al-Si Alloys Research Articles

Effect of Dissolved Gas on the Formation Ratio of Interior and Exterior Shrinkage in Hypoeutectic Al-Si Alloys

Effect of Dissolved Gas on the Formation Ratio of Interior and Exterior Shrinkage in Hypoeutectic Al-Si Alloys

Microstructural modifications and improvement in properties of a hypoeutectic Al-Si alloy dispersed with graphite particles

Microstructural modifications and improvement in properties of a hypoeutectic Al-Si alloy dispersed with graphite particles

亜共晶Ａｌ‐Ｓｉ合金の引け形態に及ぼすＳｉ量とガスの影響

亜共晶Ａｌ‐Ｓｉ合金の引け形態に及ぼすＳｉ量とガスの影響

Ａｌ‐Ｓｉ合金の耐摩耗性に及ぼすけい素量ならびにＭｇ，Ｃｕ添加の影響

Wear resistance of Al-Si alloy is increased with increasing the silicon content at low sliding speed, and severe scuffing wear occurs easily in the hypo-eutectic Al-Si alloy at high sliding speed or high load. However, desirable oxide wear by protective oxide film formed during slide is more remarkable in the hypo-eutectic Al-Si alloy than that of eutectic or hyper-eutectic alloy. An addition of Mg or Cu to Al-Si alloy is effective to improve the wear resistance but Cu is more effective than Mg. Wear resistance of AC4B is superior to AC4C, and that of AC4B is nearly same as AC8C or ADC 12. T6 treatment gives rather unpreferable effect for wear resistance of these alloys. Lubrication gives a notable effect to protect the sliding-wear of aluminum and its alloys.

Subsurface deformation in dry sliding of hypo-eutectic Al-Si alloys

The subsurface deformation during dry sliding of Al-Si alloys is studied by fragmentation of silicon particles. The size of the fragmented particles does not vary with load. The depth of deformation is found to increase with increase in normal load. This experimental observation agrees with load-deformation depth characteristics obtained by a slip line field model.

Subsurface deformation in dry sliding of hypo-eutectic Al-Si alloys

Subsurface deformation in dry sliding of hypo-eutectic Al-Si alloys

Wear characteristics, friction and surface topography observed in the dry sliding of as-cast and agehardening Al-Si alloys

Binary as-cast Al-Si alloys and two age-hardening commercial hypoeutectic and hypereutectic Al-Si alloys were studied under dry sliding conditions using a pin-bush machine. The bush was usually a hard steel. A detailed scanning electron microscopy study of worn surfaces and subsurfaces was carried out and machined surfaces were examined for comparative studies. Various surface topographies were noted depending on the contact stress and composition. Aluminium alloy deposits on the bush and subsequent back transfer of some of this deposit to the bush material clearly take place. There is an equilibrium state in this two-way transfer process. The criterion of the plasticity index is used to show that the interaction is plastic. Some elastic encounters are also possible because of work hardening of a sublayer when cracks may originate below the surface at points where the hertzian shear stress is maximum. Cracks may also propagate at the surface. It is suggested that the wear fragments are produced from the transferred material and a high modulus of elasticity of the hypereutectic alloys probably increases their propensity to wear.

Effect of stirring on the bulk solidification of hypo-eutectic and eutectic Al-Si alloys

Effect of stirring on the bulk solidification of hypo-eutectic and eutectic Al-Si alloys

Formation and Growth of Primary Alpha Solid in Hypo-Eutectic Al-Si Alloys Containing Na

Formation and Growth of Primary Alpha Solid in Hypo-Eutectic Al-Si Alloys Containing Na

人工対流により結晶微細化したアルミニウム合金鋳塊の機械的性質

Artificial convection flow caused by Lorentz-interaction between a magnetic field and a direct current created wide equiaxed zones in aluminum alloy ingots. Mechanical properties were examined for these ingots by tensile and Charpy impact test. The results obtained were as follows.In hypo-eutectic specimens, Al-Cu and Al-Si alloys solidified with artificial convection flow exhibited higher tensile strength and 0.2% proof stress than without convection flow, whereas lower elongation and reduction of area were obtained in the former case than the latter. It was postulated that the strength increased by the grain-refinement but the ductility decreased by micro-shrinkage cavities caused by violent convection flow.In Al-CuAl2 and Al-Al3Ni eutectic alloys, the tensile specimens from the ingot solidified with no convection flow exhibited higher tensile strength than the specimen with artificial convection flow when loaded parallel to the growth direction. It was suggested that this behavior was due to the presence of lamellar or rod-type intermetallic compound with reinforcement in the former but the presence of degenerated structures caused by flowing melts in the latter.In Al-Si eutectic alloys, the tensile properties were improved by artificial convection flow. It was correlated with uniform refinement of eutectic silicon phase in solidification with convection flow.Charpy impact values of the hypo-eutectic specimens depended strongly on the direction and configuration of primary aluminum-rich dendrites. In the case of eutectic specimens, it was postulated that the continuous aluminum-rich matrix resulted in higher impact values when the impact direction was parallel to the direction of solidification.

Thermal fatigue resistance of Al-Si casting alloys for pistons

Failures due to thermal fatigue often occur on the pistons made of aluminum alloys, especially on those of Diesel-engines. This paper reports the thermal fatigue resistance of Al-Si casting alloys used for pistons. The resistance to thermal fatigue was evaluated by measuring the number of cycles to failure versus total amount of strain, constraint stress or plastic strain. An apparatus for thermal fatigue testing was developed, where a high frequency induction coil was employed as a heating device. The results obtained were summarized as follows:(1) The thermal fatigue resistance of Al-Si alloy castings was in the following order:AC8B>AC8A> 15% hypersilumin> 18% hypersilumin> 23% hypersilumin. This indicates that increase in Si content lowers the resistance to thermal fatigue.(2) The resistance to thermal fatigue was related to elongation of specimens at tensile tests. Namely, materials with higher ductility showed higher resistance.(3) The hypoeutectic and eutectic Al-Si alloy castings failed owing to stress concentration by an necking effect produced by plastic deformation.(4) The hypereutectic Al-Si alloy castings, especially containing more than 18%Si, failed by preferential cracking in primary Si crystals. The cracking was caused by the difference in thhe amount of thermal expansion between Si crystals and the Al matrix.