Analysis of titanium alloys solidification structures

Balestra, Eric (2019). Analysis of titanium alloys solidification structures. University of Birmingham. Ph.D.

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Abstract

The titanium alloy solidification process is a fundamental step of alloy and cast production for industrial processes and is a source of problems, as well as the set of base properties, that influence the mechanical and heat treatments of the alloy after the solidification. In practice, some aspects of the solidification mechanism are not very well understood, such as the influence of the lamellar structure on the solidification morphology.

Experimental techniques have been designed and experiments have been performed in order to understand the features of Ti alloy solidification, in particular Ti–1023, Ti–17 and Ti–64, looking closely at the differences between alpha+beta and beta alloys. With some specific techniques, such as plasma arc melting furnace and laser melting, the absence of a lamellar structure within the beta alloys after cooling have helped in the understanding and clarification of what solidification morphology is present. Furthermore, starting from these results, the development of analysis techniques that can clarify the doubts for all Ti alloys has been achieved. The solidification conditions have been estimated and the solidification morphology found has been linked to them. Hence, with this overview, a deeper understanding of Ti alloy solidification is achieved.

Some specific details of the Ti alloy solidification morphology have been confirmed as the stability of the planar solidification morphology. Conversely, as novel results, banded-like and globular morphologies have been observed for the beta alloy. The lamellar hiding effect has been confirmed and the EDS-QMap is used in order to overcome this problem.

The understanding achieved from this work opens up the possibility of verifying and analysing current industrial processes and improving the alloy research field. A more systematic study of the titanium solidification is then suggested.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):