Patent ID: 7566504

Claim:
An iron species preform for forming a metal matrix composite by casting-in the iron species preform with an aluminum species alloy base material, the iron species preform comprising: an inner peripheral face having a section in a semicircular shape and continuously extending along a direction of a center axis; and a plurality of inner side grooves formed on the inner peripheral face at spaces in a peripheral direction, each inner side groove continuously extending along the direction of the center axis and having a section of U-shape opened to the center axis, wherein each inner side groove includes: two flat portions opposed to each other and having base ends respectively continuous to end edges continuous to the inner peripheral face; and a groove bottom portion continuously formed between depth ends of the two flat portions, and when a length from the base end to the depth end of the flat portion is A, a groove width of the inner side groove is B, a radius of curvature of a sectional shape of the groove bottom portion orthogonal to the center axis is C, an angle of inclination of the flat portion relative to a reference line in a linear shape extended from the center axis to a center of the groove width is E, and a space between the centers of the respective groove widths of the inner side grooves contiguous to each other is F, then 0.1 mm≦A≦1.0 mm, 0.5 mm≦B≦10.0 mm, C/B≦ 1.5, E≦5°, and F/B≦ 5.