Deformation-induced Microstructural Evolution during Solid Phase Processing: Experimental and Computational Studies: Deformation Induced Microstructural Evolution II
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Shaping and Forming Committee
Program Organizers: Arun Devaraj, Pacific Northwest National Laboratory; Pascal Bellon, University of Illinois at Urbana-Champaign; Suhas Eswarappa Prameela, Massachusetts Institute of Technology (MIT); Mostafa Hassani, Cornell University
Tuesday 2:30 PM
March 21, 2023
Room: 29C
Location: SDCC
Session Chair: Mostafa Hassani, Cornell University
2:30 PM Introductory Comments
2:35 PM Invited
Dynamic Recrystallization in Face-centered Cubic Particles during High-velocity Impacts: Mauricio Ponga1; 1The University of British Columbia
We investigate the dynamic recrystallization of nano- and micro-particles with high-velocity impact simulations. Molecular dynamics simulations reveal that upon a critical velocity, face-centered cubic particles recrystallize due to a synchronous emission of Shockley partial dislocations, generating a complex network, which leads to recrystallization of high misorientation angle grains. Since pressure wave decays with the distance from the impacted surface, so does the grain size, generating a new microstructure with spatial gradients within the particles. Below the critical velocity, twinning dominates the deformation mechanisms. A continuum dislocation density model is employed to extrapolated to microscopic particles. The severe plastic deformation experienced by the microparticles results in large dislocation densities and recrystallized grains of varying sizes in good agreement with experiments. These findings are relevant in the context of cold-spray and suggests the possibility of tailoring microstructure by controlling their size, orientation, and impact velocity.
3:05 PM
Heterogeneous Microstructural Evolution in Cold Sprayed Copper Coatings Using Local Zener-Hollomon Parameter and Strain: Yu Zou1; 1University of Toronto
Cold spray processing is a solid-state coating technique and an emerging method for additive manufacturing. In this study, we employ a cold spray system to deposit copper coatings over a large temperature range (373 K to 873 K) and we systematically investigate the microstructural evolutions using EBSD and TEM techniques. Diverse microstructures are observed, including recrystallized grains, annealing twins, shear bands, submicron-sized grains, deformation twins, and nanometer-sized grains. We have created the first deformation mechanism map for cold sprayed coatings to interpret and predict the heterogeneous microstructural evolutions in copper using the local Zener-Hollomon (Z) parameter and plastic strain (strain-Z-microstructure map). Such a map can be used to predict and design the microstructures of cold sprayed copper samples based on processing parameters and can also be extended to other severe plastic deformation (SPD) processes, such as cutting, extrusion, solid-phase welding, and other solid-state additive manufacturing processes.
3:25 PM
Effect of Post Deposition Heat Treatment on the Microstructural Evolution and Mechanical Properties of GRCop-42 and HR-1 Cold Spray Deposits: Bharat Jasthi1; Venkata Kandadai1; Terrence Kuca1; Marius Ellingsen2; Todd Curtis1; 1South Dakota School of Mines & Technology; 2VRC Metal Systems
The main objective of this work was to investigate the effect of post deposition heat treatment on the microstructural evolution and mechanical properties of GRCop-42 and HR-1 cold spray deposits. GRCop-42 powder blended with varying proportions of HR-1 powder (0, 15, 25, 50, 75, 85 and 100 wt.%) were cold spray deposited. The blends were motivated by the desire for gradual transitions between the two materials to eliminate stress concentrations that arise at joints between materials of differing coefficients of thermal expansion. The deposits were characterized using optical and scanning electron microscopy. Post-deposition heat treatment resulted in a recrystallized and refined microstructure in the cold spray deposits. However, coarsening of Cr2Nb precipitates in GRCop-42 deposits and precipitation of η phase in HR-1 deposits was observed with post deposition heat treatment. Post deposition heat treatment resulted in significant improvement in ductility and tensile strengths for both GRCop-42 and HR-1 deposits.
3:45 PM
Aging Kinetics in Cold Sprayed AA 7050 Material: Lorena Perez1; Luke Brewer1; 1University of Alabama
In this work, we describe the effect of post-deposition heat treatment on the nanostructure and mechanical properties of cold sprayed aluminum alloys AA7050. Cold spray deposition is showing strong potential as a repair technology and a key goal is to achieve mechanical properties comparable to wrought material (AA7050-T7451). The micro-and nanostructures of cold sprayed material are distinctly different from the wrought material. We have generated as-atomized and solutionized AA7050 feedstock powders and have cold sprayed them. These materials were then heat treated over a range of conditions to simulate artificial aging: solutionized for 1h at 480˚C and then aged at 120˚C for different dwell times. The hardness data suggests that the aging kinetics are accelerated for the cold sprayed materials, which is reasonable given their high defect density. Differential scanning calorimetry and electron microscopy are being employed to investigate this change in precipitation kinetics for cold sprayed AA7050.
4:05 PM Break
4:20 PM
Recrystallization and Microstructural Evolution in Cold Sprayed SS304L: Christopher Roper1; Anita Heczel1; Ke An2; Luke Brewer1; 1University of Alabama; 2Oak Ridge National Laboratory
This study investigates how deformation during the cold spray process effects the microstructural evolution of cold sprayed stainless steel 304L. Mechanical deformation during cold spray deposition leads to high hardness and refined microstructures particularly within prior particle interface regions. Our previous work has shown that laser heating of these cold sprayed microstructures can lead to rapid recrystallization in a matter of seconds compared to a typical furnace heat treatment of hours in cold rolled material. Additionally, using neutron diffraction it was seen that cold spraying SS304L does not lead to a significant increase in strain induced martensite as one might expect. We have recently combined precession electron diffraction, EBSD, and neutron diffraction to look at the microstructures that result from cold spray. Additionally, in situ neutron diffraction during annealing and corresponding thermal simulations have been performed to look at how these microstructures effect the recrystallization mechanisms in cold sprayed SS304L.
4:40 PM
Single Particle Impacts Experiments for Fundamental Understanding of Cold Spray Deposition with Refractory Metals: Brett Roper1; Timothy Eastman2; Andrew Deal2; Luke Brewer1; 1Univerisity Of Alabama Tuscaloosa; 2Kansas City National Security Campus
This talk will describe the deformation microstructures formed when single, refractory metal particles impact a substrate and bond. Cold spray deposition enables solid state production of three-dimensional structures. A single particle impact is the unit operation of cold spray, and it is, therefore, essential to understand how the particle microstructure is transformed by this process. Irregular and spherical tantalum and niobium particles were accelerated to supersonic velocities and then sprayed onto polished stainless steel and refractory metal substrates. Focused ion beam microscopy and electron microscopy are being used to assess the deformation microstructures at the micro- and nanoscales. The nature of the substrate causes distinct changes in the types of deformation features along the particle-substrate interface. This work was funded by Honeywell Federal Manufacturing & Technologies, LLC operating the Kansas City National Security Campus for the United States Department of Energy / National Nuclear Security Administration under Contract Number DE-NA0002839
5:00 PM
Microparticle Impact Testing at Elevated Temperatures: Ian Dowding1; Christopher Schuh1; 1Massachusetts Institute of Technology
High strain-rate mechanical testing has recently become possible using laser-launched microparticle impacts on test substrates. Here we discuss the extension of such impact tests to elevated temperatures. Using in-situ high velocity microparticle impact testing, we experimentally investigate single hard-particle impacts on a soft, low-melting temperature substrate of tin, as a function of substrate temperature. Through post mortem analysis of impact sites, we assess the conditions needed for adiabatic melting, as well as microstructural effects of plasticity in the substrate. By identifying the onset of melting for each set of initial temperature conditions, we indirectly infer the temperature rise caused by the impact and its resulting large plastic strains. This in turn allows a quantitative estimate of the amount of heat generated by the impact. Extensions of the method to evaluate adiabatic heat evolution in more detail are also briefly described.
5:20 PM
Process Effects on the Heterogenous Microctructure of an Impact Welded Interface: Anupam Vivek1; Brian Thurston1; Anil Singh1; Manny Gonzalez2; Glenn Daehn1; 1The Ohio State University; 2Air Force Research Laboratory
A high speed, oblique impact between metallic pieces can weld them together. This phenomenon, termed impact or collision welding is accompanied by jetting of the impacting surfaces and severe plastic deformation of the material at and near the interface. During this process, strain rates at the interface can easily exceed 1000/s and the metallic bonds are formed in the solid state when the right conditions are met. Adiabatic heating from plastic deformation can also lead to melting. A heterogeneous microstructure consisting of recrystallized grains, adiabatic shear bands, deformation twins and even amorphous pockets may result at the interface. Here, novel process - structure observations and relations of a wide variety of material combinations, including Al-Fe, Cu-Ti, and Cu-Ag impact welds are presented. Effects of process parameters such as impact angle, impact velocity, material thickness and boundary conditions on the microstructure are investigated through novel experiments, characterization and modeling.