Influence of Intermetallics on Complex Alloyed Brass Hardness

Abstract

The results of the study of phase composition, structure, and properties of multi-component complex alloyed wear-resistant brass are presented. The material contains aluminium, manganese, silicon, nickel, and chromium besides copper and zinc. A review of the influence of these components on the formation of intermetallics with different chemical composition and morphology is made. Based on the analysis it is revealed that the wear resistance of brass is highly dependent on the ratio of α-and β-phases and the volume fraction of the intermetallic particles. Chemical X-ray fluorescence, scanning electron microscopy (SEM) and electron-probe microanalysis (EPMA) are used. Based on the experiments it is established that alloys without chromium contain rod-shaped intermetallics based on Mn-Si compound with a ratio of length to cross sectional dimension 2–4. These intermetallics create the effect of anisotropy in an alloy. The presence of chromium in an alloy leads to the formation of equiaxial intermetallics with the chromium silicide core and manganese silicide coat; in this case the alloy is isotropic. It is established with metallographic study that the density of intermetallic compounds distribution of 50–130 thousand particles per 1 mm3 is required to archive the 291–298 HB hardness of brass. Cast ingots are made following the semi-casting method and then pressed to tube bars; the finished products are made by stamping so, the production technology can improve the mechanical characteristics of alloy.