TY - JOUR

T1 - Multimodal analysis of spatially heterogeneous microstructural refinement and softening mechanisms in three-pass friction stir processed Al-4Si alloy

AU - Escobar, Julian

AU - Gwalani, Bharat

AU - Olszta, Matthew

AU - Silverstein, Joshua

AU - Overman, Nicole

AU - Bergmann, Luciano

AU - dos Santos, Jorge F.

AU - Staron, Peter

AU - Maawad, Emad

AU - Klusemann, Benjamin

AU - Mathaudhu, Suveen

AU - Devaraj, Arun

PY - 2021/12/20

Y1 - 2021/12/20

N2 - Solid phase processing methods such as friction stir processing (FSP) offer pathways to refine the microstructure of metallic alloys through the combined action of deformation and deformation-induced heating. However, this thermomechanical coupling during FSP also leads to the occurrence of multiple competing microstructural evolution mechanisms which in turn can lead to locally varying mechanical properties, often distributed heterogeneously in the microstructure. This inherent microstructural and mechanical property heterogeneity in alloys subjected to FSP makes it rather challenging to reveal the microstructure-mechanical property relationships systematically. Therefore in this work, we systematically analyze the relationship between microstructural evolution and local microhardness in a model binary Al-4 at.% Si alloy subjected to three-pass friction stir processing. Spatially resolved high-energy synchrotron X-ray diffraction, electron backscattered diffraction, and scanning transmission electron microscopy were used to understand the heterogeneous microstructural evolution due to the FSP. Our results provide insight into how particle-stimulated grain nucleation, recovery, and recrystallization occur heterogeneously in the Al-Si alloy as a function of the distance from the stir zone, directly influencing the degree of softening. The systematic understanding developed by this work can guide future studies on the influence of FSP process parameters on the microstructural evolution mechanisms and its influence on local mechanical properties

AB - Solid phase processing methods such as friction stir processing (FSP) offer pathways to refine the microstructure of metallic alloys through the combined action of deformation and deformation-induced heating. However, this thermomechanical coupling during FSP also leads to the occurrence of multiple competing microstructural evolution mechanisms which in turn can lead to locally varying mechanical properties, often distributed heterogeneously in the microstructure. This inherent microstructural and mechanical property heterogeneity in alloys subjected to FSP makes it rather challenging to reveal the microstructure-mechanical property relationships systematically. Therefore in this work, we systematically analyze the relationship between microstructural evolution and local microhardness in a model binary Al-4 at.% Si alloy subjected to three-pass friction stir processing. Spatially resolved high-energy synchrotron X-ray diffraction, electron backscattered diffraction, and scanning transmission electron microscopy were used to understand the heterogeneous microstructural evolution due to the FSP. Our results provide insight into how particle-stimulated grain nucleation, recovery, and recrystallization occur heterogeneously in the Al-Si alloy as a function of the distance from the stir zone, directly influencing the degree of softening. The systematic understanding developed by this work can guide future studies on the influence of FSP process parameters on the microstructural evolution mechanisms and its influence on local mechanical properties

KW - Al-4Si

KW - Friction stir processing

KW - Geometric dynamic recrystallization

KW - Grain fragmentation

KW - Synchrotron X-ray diffraction

KW - Engineering

UR - http://www.scopus.com/inward/record.url?scp=85112441413&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/42befdae-6028-38a2-a0b4-5664ea903101/

U2 - 10.1016/j.jallcom.2021.161351

DO - 10.1016/j.jallcom.2021.161351

M3 - Journal articles

AN - SCOPUS:85112441413

VL - 887

JO - Journal of Alloys and Compounds

JF - Journal of Alloys and Compounds

SN - 0925-8388

M1 - 161351

ER -