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The mechanical bonding of dissimilar metals though the application of high‐pressure torsion (HPT) processing is developed recently for introducing unique ultrafine‐grained alloy systems involving microstructural heterogeneity leading to excellent mechanical properties. Considering further developments of the processing approach and the produced hybrid materials, the size effect on microstructural evolution and micromechanical responses of the mechanically bonded Al–Mg systems is evaluated. In practice, processing by HPT is conducted at room temperature on the separate Al and Mg disks having 25 mm diameter under 1.0 GPa at 0.4 rpm, and the results are compared with the mechanically bonded Al–Mg system having 10 mm diameter. The Al–Mg disks having 25 mm diameter show a general hardness distribution where low hardness appears around the disk centers, and it increases at the disk peripheries. Nanoindentation measurements demonstrate that there is excellent plasticity at the edges of the Al–Mg system with 25 mm diameter. The Al–Mg system with both 10 and 25 mm diameters show a consistent trend of hardness evolution outlining an exponential increase of hardness with increasing equivalent strain. The results are anticipated to provide a conceptual framework for the development and scale‐up of the HPT‐induced mechanical bonding technique.
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This content will become publicly available on March 1, 2026
Multi-scale Characterization of Supersaturated and Intermetallic Nanoscale Phases in Alloys Produced by High-Pressure Torsion Processing of Al and Mg Sheets
Al-Mg alloy disks were produced from Mg sandwiched between Al through 100 turns of high-pressure torsion (HPT) at 6.0 GPa at room temperature, resulting in high microhardness of Hv 300–350 in regions experiencing a nominal shear strain > ~ 390. While compositional mapping using scanning electron microscopy energy-dispersive spectroscopy (EDS) showed a uniform distribution of Mg through the disk thickness at 1.5 mm and 3.0 mm from the disk center, transmission electron microscopy EDS showed a heterogeneous distribution of Mg remained on the nanoscale. Although HPT induces enough mixing to result in face-center-cubic Al with supersaturations of Mg of up to ~ 20 at.% near the disk surfaces, β-Al3Mg2, γ-Al12Mg17 and Al2Mg intermetallic phases were identified by electron diffraction throughout the disk thickness even in regions experiencing high shear strain. This study visually captures detailed compositional heterogeneity throughout the sample thickness following intense mechanical alloying, nanoscale re-structuring and phase transformations.
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- Award ID(s):
- 2051205
- PAR ID:
- 10643558
- Publisher / Repository:
- The Minerals, Metals & Materials Society
- Date Published:
- Journal Name:
- JOM
- Volume:
- 77
- Issue:
- 3
- ISSN:
- 1047-4838
- Page Range / eLocation ID:
- 1233-1240
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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