Addition of carbonyl powders as a means of improving the compressibility and sinterability of high-alloy steel powders and the properties of materials produced from them

Abstract

tions of carbonyl nickel, iron, and alloy 50N powders in the composition range investigated were found to improve the compressibilities of the high-alloy chromium and chromium-nickel steel powders, the improvement being particularly pronounced at low pressing pressures and amounts of additions of not less than 6%. The reasons for the improvement in compressibility were twofold: First, the compressibilities of the carbonyl powders themselves were better than those of the high-alloy steel powders produced by the diffusion method (Fig. i) and, second, the carbonyl powders were of smaller particle size and were favorably situated in gaps between the less readily compressible particles of the high-alloy steel powders. Metallographic examinations of pressed specimens of the materials with carbonyl powder additions revealed that the latter were located mainly around the matrix powder particles. This was particularly noticeable in materials containing more than 6% of the addition powders. In a study of the activating effect of the additions on the sintering of the high-alloy chromium and chromiunr-nickel steel powders and also of the influence exerted by them on some properties of the resultant materials the carbonyl nickel and alloy 50N powders were employed. Tests were carried out on plain cylindrical and tensile specimens produced by pressing under