Investigations on Deformation Behavior and Microstructure of Ultrafine Grained Two Phase Al-Mn Alloy Fabricated by Confined Channel Die Pressing
An ultra-fine grained Al-1.5Mn alloy was fabricated in an oversaturated and a precipitated (Al6Mn particle) state by confined channel-die pressing (CCDP) at room temperature (RT). Specimens for microcharacterization and mechanical tests were taken from the centre area of the CCDP samples, where an equivalent strain of ε ≈1-1.4 was reached for one pass pressing. The samples were subjected to CCDP for 1, 4, 8 and 16 passes, respectively. The microstructure evolution during CCDP was investigated by transmission electron microscopy (TEM). The deformation behaviour of the ultra-fine grained Al-Mn alloy after the CCDP process was determined by compression tests at RT with different strain rates of ε& = 1× 10-4s-1, ε& = 5× 10-4s-1 and ε& = 1× 10-3s-1. The results demonstrated that the alloy with Al6Mn precipitates had a larger grain size, higher yield strength, a larger Hall-Petch coefficient, a stronger strain softening, a larger strain rate sensitivity and a smaller activation volume after CCDP compared to the oversaturated alloy. These phenomena indicate that second phase particles and solute element affect grain refinement and mechanical behaviour during and after CCDP differently.
Yuri Estrin and Hans Jürgen Maier
S. J. Mu et al., "Investigations on Deformation Behavior and Microstructure of Ultrafine Grained Two Phase Al-Mn Alloy Fabricated by Confined Channel Die Pressing", Materials Science Forum, Vols. 584-586, pp. 697-702, 2008