Athermal and Thermal Limits of the Grain Refinement by SPD

Martin Hafok; Reinhard Pippan

doi:10.4028/www.scientific.net/MSF.584-586.938

Paper Titles

Effect of Cryorolling Strain on Precipitation Kinetics of Al 7075 Alloy
p.911

Characteristic Features and Thermal Stability of Molybdenum Processed by Different Ways of Severe Plastic Deformation
p.917

Tailoring the Magnetic Properties of Ferritic Alloys by HPT
p.923

Continuous Recrystallization Phenomenon in High Purity Copper during Equal Channel Angular Pressing up to High Strain at Room Temperature
p.929

Athermal and Thermal Limits of the Grain Refinement by SPD
p.938

Annealing Behavior of ECAP Deformed Aluminum Alloy 3103
p.944

Magnetic Parameters of R₂Fe₁₄B Compounds with Nanograin Structure
p.950

Martensitic Transformation in Fe-Ni Alloys Nanostructured by Ball Milling
p.955

Thermal Stability of Mechanical Properties of Copper after Equal-Channel Angular Pressing
p.960

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Athermal and Thermal Limits of the Grain Refinement by SPD

Abstract:

Severe plastic deformation, SPD, enables the grain refinement of bulk materials. However, at strains larger than a critical value, no further microstructural refinement can be observed. This regime is denoted as saturation region of the microstructural size. It will be shown that this regime can be divided into a thermal and an athermal part. The transition between these two regimes was examined in an Al-3wt.%Mg alloy. The single phase alloy was deformed by high pressure torsion (HPT) at various temperatures and different rotational speeds. During the HPTdeformation the flow stress was measured by a torque cell in a temperature range between -196°C (evaporation temperature of the liquid nitrogen) and 450°C. The temperature and the strain rate dependent behavior reveal a shift of the onset of the thermal activated regime towards higher temperatures by an increase of the strain rate.