Plastic deformation of Ti-6Al-4V micro-pillars at room temperature

Liu, Zhaoran (2017). Plastic deformation of Ti-6Al-4V micro-pillars at room temperature. University of Birmingham. Ph.D.

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Abstract

In this work, the deformation behaviour of Ti-6Al-4V micro-pillars was studied via compression tests at room temperature. Micro-pillars containing either the single α phase region or both α and β phases were prepared and either prismatic <a> slips or <c+a> slips were activated. Thin foils for TEM study were prepared using the FIB from the selected deformed pillars. STEM was used to image dislocations and their interaction with the α/β interfaces. Sample yield strength has been observed in all groups of micro-pillars and its relationship with the β phase, α/β interface, orientation and extrinsic sample size was discussed. The β phase is proved weaker than the α phase and the α/β interfaces behaviour as both the barriers and sources of dislocations. The magnitude of influence depending on the volume fraction, orientation and morphology of the β phase and the α/β interfaces. The work-hardening rate is related to the orientation of micro-pillars and the α/β interfaces in the micro-pillars. The strain bursts can be suppressed by the α/β interface and smaller sample size. The sample with smaller size expressed the larger strain burst in the stress-strain curves. The orientation influences the number and magnitude of strain bursts.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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