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Investigation Of Deformation And Failure Mechanisms In Nanoindentation Mechanics, Yuzhi Xia
Investigation Of Deformation And Failure Mechanisms In Nanoindentation Mechanics, Yuzhi Xia
Doctoral Dissertations
This dissertation further extends nanoindentation to study the initiation of plasticity in single crystals in nanoscale stressed volumes, to the instrumented tests for damage evaluation and monitoring, and to the fundamental issues in deformation and failure mechanisms in relationship to the defect evolutions.
In the first project, model Fe-Cr, Fe-Ni and Fe-Cr-Ni alloys that are the basis of many structural steels were synthesized as single crystals and characterized. The compositions investigated were Fe-15Cr, Fe-30Cr, Fe-30Ni and Fe-15Cr-15Ni (atomic percent). Several key mechanical properties were determined which will be useful in further studies of irradiation/deformation-induced defects. Incipient plasticity and slip characteristics …
Deformation Of A Face-Centered Cubic Fecocrmnni High Entropy Alloy, Chao Zhu
Deformation Of A Face-Centered Cubic Fecocrmnni High Entropy Alloy, Chao Zhu
Doctoral Dissertations
A polycrystalline, face-centered cubic high entropy alloy (HEA) FeCoCrMnNi was investigated by nanoindentation and stress relaxation. A literature review on HEAs was presented in Chapter 1 and a description of methodology was followed in Chapter 2.
In Chapter 3, the nature of incipient plasticity was characterized with instrumented indentations over various loading rates and temperatures. The maximum shear stress for initiating the incipient plasticity attained the theoretical strength and was relatively insensitive to grain orientation. However, it strongly depended upon the temperature, indicating a thermally activated nucleation process. The estimated activation energy and volume signify that the nucleation is mediated …