Rheocasting of new aluminum-titanium alloys

• Grant number: 22/05050-5
• Support type: Regular Research Grants
• Duration: September 01, 2022 - August 31, 2024
• Field of knowledge: Engineering - Mechanical Engineering - Manufacturing Processes
• Principal researcher: Eugênio José Zoqui
• Grantee: Eugênio José Zoqui
• Home Institution: Faculdade de Engenharia Mecânica (FEM). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

The processing of metallic alloys in the semi-solid state, (SSM or S2P), is nothing more than the forming of materials in the mushy state. Among the main processes, Rheocasting and Thixoforming stand out, which compete with die-casting technology (permanent mold injection) and with hot forging operations (in open or closed die). Metal alloys of the Al-Si and Mg-Al system are commercially processed, common to the foundry industry, which, however, have limited mechanical properties. For Al-Si alloys, Rheocasting is carried out with the injection under pressure of a mixture composed of solid Al-alpha particles immersed in liquid, which has a composition close to the eutectic Al-Si. The present project seeks to improve the development of new alloys, as well as their processing method, in such a way as to obtain high-performance structural parts via Rheocasting processing. Al-Ti-Mg alloys will be produced, processed, and characterized with a view to their application in the manufacture of parts with complex geometry for the electronics industry, such as heat sinks and antennas. Al-Ti-(Zn-Cu-Mg) alloys similar to alloys 2024, 5056 and 7075 will also be tested, for applications in the metal-mechanical sector, aiming at structural parts with high mechanical strength. These are alloys with twice the mechanical strength of Al-Si alloys. The test compositions were the object of development with thermodynamic simulation techniques via Calphad. For both cases, the forming mass will be formed by a mixture of solid particles of TiAl3, enriched with solid Al-alpha, which in turn will be formed using a technique analogous to the GISS processing, (Gas Induced Semi-Solid), in a liquid medium consisting mostly of Al-alpha. Metal alloys with such compositions are not processed by injection under pressure due to the incorporation of gases during processing, as well as due to the high shrinkage generated by the solid-liquid transformation, which leads to the formation of porosities and shrinkage cracks respectively. Only processing in the semi-solid state can solve both problems. In addition to the rheological characteristics, which determine the processing conditions, the mechanical properties of the products will also be evaluated, as will specific characteristics, such as thermal and electrical conductivity, corrosion resistance, etc. Heat treatments to optimize these properties will also be evaluated. (AU)