Effect of Geometry and Architecture on the Fatigue Performance of Additively Manufactured Nickel Alloy for Aerospace Applications

Supervisor: Dr Andrew R. Hamilton
Co-supervisor Prof. Ian Sinclair

Project description

Laser powder bed fusion (LPBF) is a form of additive manufacturing that involves spreading a layer of powder and scanning a laser to selectively fuse the powder into a single layer of the part geometry. By repeating this process layer-by-layer, LPBF can shape metal alloys into complex geometries (e.g., porous architectures, thin-walls, curved shapes, and tortuous flow paths) that would be difficult or impossible to produce otherwise, and that enhance functionalities such as lightweight load-bearing, heat transfer, metering, mixing and reacting. Among the range of compatible metal alloys that have been developed for LPBF, Inconel nickel alloys are attractive for their high strength, toughness, creep and corrosion resistance under high temperature operating conditions. This range of functions and properties of LPBF Inconel alloys is attractive for manufacturing combustion and propulsion components and systems for use in aerospace, among other applications. LPBF is a complicated manufacturing process with many parameters that affect the structure and properties the materials and parts it produces. Controllable process parameters primarily include laser power, scan velocity and spacing, scan pattern, and powder layer thickness; adjusting these will change the amount of heat input during fusion, the thermal history (heating and cooling rate), and the metallurgical structure and properties that result. Additionally, there are process parameters that cannot be directly controlled; these include the size and shape of the part, which determines the conductive pathways for heating and cooling, as well as spreading and compaction of powder and the resulting distribution of particle sizes, which affects heat absorptivity and consolidation of free pore space during fusion. These uncontrolled parameters are non-uniform throughout the process and thus contribute to spatially varying structure and properties throughout a LPBF part. Certifying LPBF parts for use in aerospace applications requires the ability to characterise, explain, and predict the lifetime of LPBF parts with a high degree of certainty, but the complex and heterogeneous process-structure-property relationships of these materials is a significant challenge to doing so. The aim of this project is to address this challenge for LPBF Inconel nickel alloys. In order to do so, LPBF will be used to produce specimens with representative geometric features. The structure and shape will be measured using microscopic and volumetric imaging. A mechanical testing campaign will be carried out to determine fatigue performance, and predictive models will be developed to relate this to key process-structure-property relations. The results will be disseminated to end-users in the aerospace industry, and will help contribute to the development and certification of the next generation of more efficient combustion and propulsion systems, and many other potential applications.

Entry Requirements
A good undergraduate degree (at least a UK 2:1 honours degree, or its international equivalent).

Closing date: applications should be received no later than 31 August 2020.

Funding: tuition fees for EU/UK students plus for UK students, a stipend of £15,285 per annum upto 3.5 years.

How To Apply

Apply online, select the academic session 2020-21 “PhD Eng & Env (Full time)” as the programme. Enter Andrew R. Hamilton the proposed supervisor.

Applications should include:
Curriculum Vitae
Two reference letters
Degree Transcripts to date
Apply online: https://www.southampton.ac.uk/courses/how-to-apply/postgraduate-applications.page