Thermo mechanical effects on Ti deformation mechanisms in cold dwell

Cyclic loading is characteristic of components in an aero-engines, where they are exposed to both low frequency (e.g. take off and landing), and high frequency (e.g vibration) loading. Therefore it is very important to understand what gives Ti alloys their fatigue strength, and in particular how it is affected by the load frequency and by other environmental parameters like temperature.

Through extensive testing, engineers have developed sound empirical relationships between fatigue strength and the microstructure of different Ti alloys. However, the actual physical mechanisms controlling this behaviour are not fully understood. This gap in our knowledge makes it difficult to account for material and/or operating conditions outside previous experience. It also makes it difficult to understand how the alloy could be improved, so that less of it can be used, which would help build lighter, more efficient aero-engines.

The aim of this project is to improve our understanding of how these important alloys deform at the micro-structural scale during low frequency cyclic loading, and at different temperatures. Working in collaboration with Rolls-Royce, you will use new experimental techniques developed at the University of Manchester to measure the deformation of these alloys with sub-micron spatial resolution, helping to unravel the physical process that lead to fatigue failure and damage and understand how they can be avoided. This work will make use of unique state-of-the-art facilities available at the Royce Institute at Manchester (www.royce.ac.uk), including high-resolution electron microscopes with in-situ testing capability, machines for 3-dimensional crystal orientation mapping, and high resolution transmission electron microscopes.

The successful candidate will join a large team of researchers (10+) working on titanium alloys at Manchester, and collaborate with scientists and engineers at Rolls-Royce and other UK and international universities. The project provides access and training on some of the most advanced characterisations methods currently available and sound training in advanced data analysis using open source packages. There will also be opportunities to visit Rolls-Royce and other partner organisations.

The EPSRC Centre for Doctoral Training in Advanced Metallic Systems was established to address the metallurgical skills
gap, highlighted in several reports [1-3] as a threat to the competitiveness of UK industry, by training non-materials
graduates from chemistry, physics and engineering in a multidisciplinary environment. Although we will have supplied ~140
highly capable metallurgical scientists and engineers into industry and academia by the end of our existing programme,
there remains a demonstrable need for doctoral-level training to continue and evolve to meet future industry needs. We
therefore propose to train a further 14 UK based PhD and EngD students per cohort as well as 5 Irish students per
cohort through I-Form.

Manufacturing contributes over 10% of UK GVA with the metals sector contributing 12% of this (£10.7BN [4,5]) and
employing ~230,000 people directly and 750,000 indirectly. It is estimated that ~2300 graduates are required annually to
meet present and future growth [5]. A sizeable portion of these graduates will require metallurgical expertise and current
numbers fall far short. From UK-wide HESA data, we estimate there are ~330 home UG/PGT qualifiers in materials and
~35 home doctoral graduates in metallurgy annually, including existing AMSCDT graduates, so it is unsurprising that
industry continues to report difficulties in recruiting staff with the required specialist metallurgical knowledge and
professional competencies.

As well as addressing this shortfall, the CDT will also impact directly on the companies with which it collaborates, on the
wider high value manufacturing sector and on the UK economy as a whole, as follows:

1. Collaborating companies, across a wide range of businesses in the supply chain including SMEs and research
organisations will benefit directly from the CDT through:

- Targeted projects in direct support of their business and its future development and competitiveness.
- Access to the expertise and facilities of the host institutions.
- Involvement in the training of the next generation of potential employees with advanced technical and leadership skills
who can add value to their organisations.

2. The UK High-Value Manufacturing Community will benefit as the CDT will:

- Develop the underpinning science and advanced-level knowledge base required by future high technology areas, where
there is high expectation of gross added value.
- Provide an enhanced route to exploitation, by covering the full spectrum of technology readiness levels.
- Ensure dissemination of knowledge to the sector, through student-led SME consultancy projects, the National Student
Conference in Metallic Materials and industry events.

3. The wider UK economy will benefit as the CDT will:

- Promote materials science and engineering and encourage future generations to enter the field, through outreach
activities developed by the students that will increase public awareness of the discipline and its contribution to modern
life, and highlight its importance to future innovation and technologies.
- Develop and exploit new technologies and products which will help to maintain a competitive UK advanced
manufacturing sector, ensure an internationally competitive and balanced UK economy for future generations and
contribute to technical challenges in key societal issues such as energy and sustainability.

References:
1. Materials UK Structural Materials Report 2009
2. EPSRC Materials International Review 2008
3. EPSRC Materially Better Call 2013
4. The state of engineering, Engineering UK 2017
5. Vision 2030: The UK Metals Industry's New Strategic Approach, Metals Forum