Grain refinement and properties of alloys of Al, Mg and Ti with ultrafine grains produced by equal channel angular with back pressure

• Grant number: 12/17353-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2012
• End date: November 30, 2013
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Alberto Moreira Jorge Junior
• Grantee: Denis Prado Santos
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

The application of ECAP can be restricted during the processing of hard-to-deform and low-ductility materials. It is known that in order to effectively refine the structure and achieve superior properties ECAP should be realized in several cycles. The high level of accumulated strain can result in crack initiation and failure of samples, which is connected with non-conformance of ductility and the level of specific pressures holding back the sample failure. The deformation capacity of the material improves at elevated temperatures. However, the recovery processes and structure recrystallization do not allow achieving the maximum degree of refinement and extraordinary properties. One of the effective ways to enhance the deformability resource during ECAP is an increase of the hydrostatic pressure imposed on a billet using backpressure. This increases the workability of the material at higher specific stress in the shearing area including at room temperature Main scientific task to be solved under this project will be the analysis of possibilities to apply ECAP with back-pressure to hard-to-deform and low-ductility alloys. The task is connected with the maximum refinement of their structure, which opens ways to fabricating superior service properties in them, where Mg, Al, and Ti alloys will be used as materials for study in the project. During experiments, a die-set for ECAP with backpressure specially designed at Universidade Federal de São Carlos will be used. In particular computer-controlled ECAP die where it is possible to control the forward and backward pressures and the velocities of both punches. The microstructure of the alloys subjected to ECAP will be studied with the help of X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM and SEM), and differential scanning calorimetry (DSC). The mechanical properties of the materials will be determined via microhardness measurements and tensile tests.(AU)