TY - JOUR

T1 - Rapid grain refinement and compositional homogenization in a cast binary Cu50Ni alloy achieved by friction stir processing

AU - Escobar, Julian

AU - Gwalani, Bharat

AU - Silverstein, Joshua

AU - Ajantiwalay, Tanvi

AU - Roach, Christian

AU - Bergmann, Luciano

AU - dos Santos, Jorge F.

AU - Maawad, Emad

AU - Klusemann, Benjamin

AU - Devaraj, Arun

N1 - Publisher Copyright: © 2023

PY - 2023/8/1

Y1 - 2023/8/1

N2 - Friction stir processing (FSP) has been increasingly adopted for joining and processing materials in automotive, aerospace, and industrial construction. During FSP, a dynamic competition between high-speed shear deformation and deformation-induced heating brings about a complex competition between multiple dynamic microstructural evolution mechanisms making it difficult to predict the microstructural evolution pathway. Hence, improved understanding of microstructural evolution mechanisms during FSP can be beneficial for continued growth in the adoption of FSP for demanding applications of future. Towards this goal, this study uses a model binary Cu – 50 at.% Ni alloy to clarify the effect of single and double pass FSP on the microstructural evolution of a coarse grained and compositionally heterogeneous cast microstructure. High energy synchrotron X-ray diffraction, electron backscatter diffraction, and nanoindentation are used to clarify the microstructural evolution due to FSP. The process of compositional homogenization of as-cast segregations is studied by energy dispersive spectroscopy and atom probe tomography. Our results show that a single fast FSP pass at 30 mm.s−1 produces a 100 μm deep layer of submicrometric and hall-petch hardened CuNi grains. The initial cast compositional heterogeneities in a micrometric scale is rapidly transformed to nano-sized domains, mainly confined at grain boundaries. Double pass FSP increases the penetration depth of the processed layer and leads to a 2.9 times grain growth relative to single pass FSP. Grain fragmentation, discontinuous dynamic recrystallization, grain growth, and twinning mechanisms are discussed. These results highlight the value of FSP for ultrafast grain refinement and compositional homogenization of cast alloys.

AB - Friction stir processing (FSP) has been increasingly adopted for joining and processing materials in automotive, aerospace, and industrial construction. During FSP, a dynamic competition between high-speed shear deformation and deformation-induced heating brings about a complex competition between multiple dynamic microstructural evolution mechanisms making it difficult to predict the microstructural evolution pathway. Hence, improved understanding of microstructural evolution mechanisms during FSP can be beneficial for continued growth in the adoption of FSP for demanding applications of future. Towards this goal, this study uses a model binary Cu – 50 at.% Ni alloy to clarify the effect of single and double pass FSP on the microstructural evolution of a coarse grained and compositionally heterogeneous cast microstructure. High energy synchrotron X-ray diffraction, electron backscatter diffraction, and nanoindentation are used to clarify the microstructural evolution due to FSP. The process of compositional homogenization of as-cast segregations is studied by energy dispersive spectroscopy and atom probe tomography. Our results show that a single fast FSP pass at 30 mm.s−1 produces a 100 μm deep layer of submicrometric and hall-petch hardened CuNi grains. The initial cast compositional heterogeneities in a micrometric scale is rapidly transformed to nano-sized domains, mainly confined at grain boundaries. Double pass FSP increases the penetration depth of the processed layer and leads to a 2.9 times grain growth relative to single pass FSP. Grain fragmentation, discontinuous dynamic recrystallization, grain growth, and twinning mechanisms are discussed. These results highlight the value of FSP for ultrafast grain refinement and compositional homogenization of cast alloys.

KW - Engineering

KW - Discontinuous dynamic recrystallization

KW - Friction stir processing

KW - Miscible alloys

KW - Synchrotron X-ray diffraction

UR - http://www.scopus.com/inward/record.url?scp=85160344867&partnerID=8YFLogxK

U2 - 10.1016/j.matchar.2023.112999

DO - 10.1016/j.matchar.2023.112999

M3 - Journal articles

VL - 202

JO - Materials Characterization

JF - Materials Characterization

SN - 1044-5803

M1 - 112999

ER -