Abstract: A hybrid fiber-reinforced plastic composite material comprising a matrix of a plastic and hybrid fibers consisting of inorganic fibers and at least one kind of fibers selected from the group consisting of carbon fibers, glass fibers, boron fibers, aramide fibers and silicon carbide fibers having a carbon core, wherein(a) the inorganic fibers are inorganic fibers containing silicon, either titanium or zirconium, carbon and oxygen and being composed of(i) an amorphous material consisting substantially of Si, M, C and O where M represents Ti or Zr, or(ii) an aggregate consisting substantially of ultrafine crystalline particles with a particle diameter of not more than 500 .ANG. of .beta.-SiC, MC, a solid solution of .beta.-SiC and MC and MC.sub.1-x, and amorphous SiO.sub.2 and MO.sub.2, where M is as defined and x is a number represented by 0<x<1, or(iii) a mixture of the amorphous material (i) and the aggregate (ii),(b) the composite material has an interlayer shear strength of at least about 9 kg/mm.sup.

Abstract: An inorganic fiber-reinforced metallic composite material comprising a matrix of a metal or its alloy and inorganic fibers as a reinforcing material, characterized in that(a) the inorganic fibers are inorganic fibers containing silicon, either titanium or zirconium, nitrogen and oxygen and being composed of(i) an amorphous material consisting substantially of Si, M, N and O, or(ii) an aggregate consisting substantially of ultrafine crystalline particles with a particle diameter of not more than 500 .ANG. of Si.sub.2 N.sub.2 O, MN, Si.sub.3 N.sub.4 and/or MN.sub.1-x, and amorphous SiO.sub.2 and MO.sub.2, provided that in the above formulae, M represents titanium or zirconium, and x is a number represented by 0<x<1, or(iii) a mixture of the amorphous material (i) and the aggregate (ii), and(b) said metal is selected from the group consisting of aluminum, magnesium, and titanium, or(c) said alloy is selected from the group consisting of aluminum alloys, magnesium alloys and titanium alloys.

Abstract: An inorganic fiber-reinforced ceramic composite material comprising a matrix of a ceramic and inorganic fibers as a reinforcing material, characterized in that(a) the inorganic fibers are specified inorganic fibers containing silicon, either titanium or zirconium, nitrogen and oxygen, and(b) the ceramic is at least one material selected from the group consisting of carbides, nitrides, oxides, glass ceramics, graphite and specified inorganic materials containing silicon, either titanium or zirconium, nitrogen and oxygen.