Abstract: This invention provides a self-lubricating composite material which has excellent strength and oxidation resistnce at a high temperature and can be used in air and in vacuum, and a production method thereof, the composite material is a Cu--Ni--Sn type composite sintered body containing 20 to 70 vol % of mixed particles of graphite and WS.sub.2 as the solid lubricant components and having a porosity of not greater than 25 vol %, and a matrix is a two-phase alloy comprising Cu--Ni alloy particles and an Sn single phase or an Sn--Ni intermetallic compound dispersed uniformly in the grain boundary of the alloy particles and firmly bonding them, and this matrix encompasses the solid lubricant particles. The matrix consists of 5 to 40 wt % of Ni, 4 to 15 wt % of Sn and the balance of Cu and unavoidable impurities as the alloy composition.

Abstract: An Fe-Si alloy powder magnetic core comprises an alloy powder of an average particle diameter of 10-100 .mu.m, produced by water atomization, in which the composition by weight of the alloy powder is 2-12% silicon and 0.05-0.95% oxygen with the balance being essentially iron. The process of manufacturing the powder magnetic core is also disclosed.

Abstract: This invention relates to a coaltar pitch based carbon fiber having a high Young's modulus produced by using coaltar pitch as a starting material, which has a microstructure with a preferred orientation parameter (HWHM) of 10.degree. or less, a crystallite size (Lc(002)) of not more than 25 nm and not less than 18 nm and an interlayer spacing (d002) of not more than 0.345 nm and not less than 0.338 nm as determined by X-ray diffraction, and has a magnetoresistance of less than -0.40% and not less than -2.00% as measured by applying a magnetic field of 10 KG perpendicular to the fiber axis at liquid nitrogen temperature, and a Young's modulus of 55 ton.multidot.mm.sup.-2 or more, preferably 75 ton.multidot.mm.sup.-2 or more. The carbon fiber of this invention has a high Young's modulus, is flexible, and does not split in the fiber axis direction, and therefore it is easy to handle, is good in workability, and contributed also to improvement of the production efficiency.