Itaru Shirayanagi

Infiltration of fibrous preform by molten aluminum in a centrifugal force field

The pressure to infiltrate molten aluminum into alumina short-fiber preforms was generated by centrifugal force, and it was proved that centrifugal force is effective as a motive force for the infiltration and sound composites that are produced. The initiation pressure of the infiltration was also calculated and obtained clearly. The start pressure agreed well with the threshold pressure obtained theoretically. The characteristics of the infiltration in the preform was discussed using a one-dimensional solution of D’Arcy’s law in a centrifugal force field. It was made clear that when preform surface pressure is low, the region having lower pressure than the threshold pressure appears in the infiltrated region.

K2O · 6TiO2 whisker-reinforced aluminium composite by a powder metallurgical method

Amelioration de la resistance du materiau composite par une methode de metallurgie des poudres. Etude de la relation entre la resistance a la traction et la fraction volumique de barbes dans le materiau

Effect of cold rolling on the mechanical properties of Al/alumina short fiber composite.

Tensile strength and workability of Al/alumina short fiber composites fabricated by the high pressure casting method and cold rolled were investigated. The cold work of the composites was possible up to 20% of volume fraction of alumina fiber. The rate of the strength increase at the initial stage of rolling was large in high alumina fiber content composites and the limit of the strength increase was 21-22kgf/mm2 in all composites. The high temperature tensile strength decreased rapidly with temperature, and the strength also decreased to those of as-cast composites by annealing at 300°C. The increase in tensile strength seemed to be caused not by the degrees of fiber orientation, but by work hardening. The fracture strain of the composites decreased with volume fraction of fiber.

Fatigue of Alumina Short Fiber / Aluminium Alloy Composites

Cyclic bending fatigue tests were performed on alumina short fiber reinforced JIS AC8A alloys, to examine the effects of volume fraction of fibers and nonfibrous inclusions (shots) on the S-N curve. Fatigue limit stress rose with increasing volume fraction of fibers and the effect of shots was very small when shots content was less than 0.1%. Cyclic fatigue crack propagation was also measured on the composites. The sensitivity of the composites to pre-crack increased greatly with increasing volume fraction of fibers.