Recovering precipitation strengthening in additive friction stir deposition builds: heat-treatment design for microstructure control and property improvement

About the Project

Supervisory Team: Dr Dikai Guan and Prof Pedro Rivera

This project aims to unlock stronger 3D-printed metals. It pioneers new heat-treatment strategies to recover and even surpass the strength of additively manufactured light alloys. Using advanced microscopy, modelling and mechanical testing, you’ll design process–microstructure-properties maps that transform low-strength printed parts into high-performance components for aerospace, transport and hydrogen technologies.

Additive Friction Stir Deposition (AFSD) is a rapidly emerging solid-state additive manufacturing that avoids melting and solidification. By combining intense frictional heating and severe plastic deformation, AFSD can fabricate fully dense metallic components with fine, equiaxed grains. However, when age-hardenable alloys are processed, the intense deformation and elevated temperature dissolve the fine strengthening precipitates and trigger over-ageing or coarsening. As a result, as-deposited components are typically 30–50 % softer than the wrought feedstock despite having refined and equiaxed grains.

This project aims to design and validate post-build heat treatments that restore or surpass ≥100 % of wrought strength in AFSD aluminium and magnesium alloys by re-engineering precipitate populations while retaining dynamic recrystallisation-refined grains.

This project aims to:

• map the as-built state: quantify precipitate dissolution, grain size and orientation gradients vs. AFSD process parameters using our existing 18-parameter dataset
• develop tailored heat-treatment strategies: test direct ageing (DA), solution–quench–age (SQA), and stepped ageing to refine precipitates without excessive grain growth
• build predictive models: link AFSD thermal/strain history to precipitation kinetics to recommend heat-treatment windows for strength recovery
• validate mechanical performance: recover yield/ultimate tensile strength and hardness at room temperatures and benchmark anisotropy against wrought data

The expected outcomes of the project are the following:

• Scientific: first integrated processing → microstructure → heat treatment → property maps for AFSD, enabling predictive design of strengthening treatments
• technological: turn low-strength as-built AFSD Al and Mg into high-performance, structural parts for industry applications

Entry Requirements:

You must have a UK 2:1 honours degree, or its international equivalent.

Fees & Funding

We offer a range of funding opportunities for both UK and international students. Horizon Europe fee waivers automatically cover the difference between overseas and UK fees for qualifying students.

Competition-based Presidential Bursaries from the University cover the difference between overseas and UK fees for top-ranked applicants.

Competition-based studentships offered by our schools typically cover UK-level tuition fees and a stipend for living costs for top-ranked applicants.

Funding will be awarded on a rolling basis, so apply early for the best opportunity to be considered.

For more information, please visit our postgraduate research funding pages.

How to Apply:

Apply now

You need to:

• choose programme type (Research), 2026/27, Faculty of Engineering and Physical Sciences
• select Full time or Part time
• search for programme PhD Engineering & the Environment (7175)
• add name of the supervisor in section 2 of the application

Applications should include:

• your CV (resumé)
• 2 academic references
• degree transcripts and certificates to date
• English language qualification (if applicable)