TEM Studies on the Effect of Nature of Precipitates in Al-Li Alloy on Microstructural Evolution during Severe Plastic Deformation

Sivaswamy Giribaskar; Gouthama Gouthama; Rajesh Prasad

doi:10.4028/www.scientific.net/MSF.584-586.411

Paper Titles

Influence of a Slip Plane Orientation with Respect to the Shear Plane of ECAP on Microstructure of Copper Single Crystal Subject to One Pressing at Room Temperature
p.387

Grain Refinement of Pure Copper by ECAP
p.393

Activation Volume in Fine Grained Metals from Stress Relaxation and Nano-Indentation
p.399

Ultimate Strength of a Tungsten Heavy Alloy after Severe Plastic Deformation at Quasi-Static and Dynamic Loading
p.405

TEM Studies on the Effect of Nature of Precipitates in Al-Li Alloy on Microstructural Evolution during Severe Plastic Deformation
p.411

Strengthening of Nickel Deformed by High Pressure Torsion
p.417

TEM Study of Local Disordering: A Structural Phase Change Induced by High-Pressure Torsion
p.422

Bulk Al Materials from Back Pressure Equal Channel Angular Consolidation of Mechanically Milled Particles
p.428

3D Tomographic EBSD Measurements of Heavily Deformed Ultra Fine Grained Cu-0.17wt%Zr Obtained from ECAP
p.434

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TEM Studies on the Effect of Nature of Precipitates in Al-Li Alloy on Microstructural Evolution during Severe Plastic Deformation

Abstract:

Equal channel angular extrusion (ECAE), involving intense plastic straining under high applied pressure is generally recognized and extensively studied top down approach for producing bulk ultra-fine grained (UFG) metallic materials, and even going down in size to the nanometer range. In this research efforts are made to identify conditional under which grains with size less than 100 nm form after ECAE. Evolution of microstructure of Al-Li based alloy processed by ECAE is analyzed using transmission electron microscopy (TEM). Observations on the effect of precipitates/second phase particles in the sample on the deformation characteristics and their role on the increased degree of grain fragmentation process is highlighted. Samples of Al-Li based alloy are solutionized, quenched and aged at different temperatures to obtain well formed precipitate laths/plates before subjecting to ECAE. During the deformation process these precipitates disintegrate into fragments and get dispersed into the Al matrix. The fragments of a few nanometers size bring about drastic changes in the flow as well as the recovery characteristics of processed samples. Evidence for dynamic recrystallisation taking place during the ECAE processing is presented. It was observed that optimal thermal treatment leads to more effective grain refinement and consequently an ultra-fine grained microstructure could be achieved even after single pass in Al-Li based alloy containing precipitates and second phase particles.