<p><a>Aluminum (Al) alloys have been widely
used in </a>industry as
light-weight structural materials. However, the mechanical strength of
the strongest Al alloys is still much lower than most high-strength steels.
This thesis aims to investigate the fabrication and mechanical behaviors of
nanotwinned high-strength Al alloys and multilayers.</p>
<p>Twin boundaries are
special grain boundaries with mirror symmetry. Twin boundaries can generate
slip discontinuity and block the transmission of dislocations, and serve as
dislocation sources to accommodate plasticity. However, twinning in Al is rare
due to its high stacking fault energy and low unstable stacking fault energy.
In this thesis, we used multiple methods to introduce high-density twins into
Al and achieve outstanding mechanical properties and thermal stability. </p>
<p>Certain type of solutes can greatly increase the twin
density in Al by decreasing the stacking fault energy of Al and retarding the
detwinning process. Nanotwinned Al-Ni and Al-Ti binary alloys fabricated by
magnetron sputtering show high strength, good deformability, and unique
deformation mechanisms. Furthermore, deformation and thermal stability of
binary nanotwinned Al alloys can be enhanced by adding a third or fourth solute
element. </p>
<p>Interfaces can
facilitate twin formation in Al as well. High-density twins and stacking faults
were introduced into Al by using Al/Ti layer interfaces. Nanotwinned Al/Ti
multilayers have ultra-high strength, superb deformability and thermal
stability. This thesis provides promising pathways to fabricate Al alloys and
composites with high strength and good thermal stability.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/12657044 |
| Date | 10 September 2022 |
| Creators | Yifan Zhang (9127289) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/MECHANICAL_PROPERTY_AND_DEFORMATION_MECHANISMS_OF_NANOTWINNED_ALUMINUM_ALLOYS_AND_MULTILAYERS/12657044 |
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