Complex modification of AlSi9Cu3(Fe) alloy by using cobalt, vanadium and molybdenum

Abstract

Aluminum casting alloys of the Al-Si and Al-Si-Cu systems are among the most widely used materials for machine building. Their wide use is associated with low cost, high manufacturability, excellent ability for multiple recycling and sufficient level of mechanical properties. Increasing of Al-Si-Cu alloys mechanical characteristics always remains as a relevant task, which is often solved by several components modification. Presented work is dedicated to investigation of Co, V and Mo complex influence on the structural phase state and mechanical properties of the widely used AlSi9Cu3(Fe) alloy. All modifying additives were added in the amount of 0.1-0.2 wt. %. At the same time, their total content did not exceed 0.5 wt. %. It is shown that the complex modification of AlSi9Cu3(Fe) with cobalt and vanadium contributes to a significant grain refinement and increasing strength of the alloy by more than 20% while maintaining plasticity. At the same time, cobalt mainly performs the function of a modifier of eutectic components, and vanadium plays the role of a grain refiner. Simultaneous modification of the alloy with vanadium and molybdenum ensures refining of all structural components and strength elevating. Both components perform the function of nucleation. The simultaneous addition of cobalt and molybdenum shows the effect of cobalt on eutectic components. Molybdenum actually does not have a nucleating effect and is mainly goes to iron-containing phases. As a result, average mechanical properties can be observed. Triple modification makes it possible to obtain maximum refining of all structural-phase components and increase the strength of the alloy. The highest microhardness of such alloys indicates potentially high level of mechanical properties at elevated temperatures. Keywords: cast aluminum alloys, modification, AlSi9Cu3(Fe), structure, phase composition, mechanical properties.