A life in metals
and discovery
Celebrating National Engineering Day: Dr Minh-Son Pham’s inspiring journey in materials science, metals, and discovery.
It is no exaggeration to say that Dr Minh-Son Pham has worked with metals all his life. As an academic, his research has ranged from the performance of steels in nuclear power plants to the manufacture of car bodies, and from 3D printing with metals to the structural integrity of alloys used in aerospace. But long before this work, as a child in Vietnam, he helped his family scrape a living by picking scrap metal out of landfills.
“In a way I’ve come full circle, from my first ‘job’ in the landfill to my work now, which is focused on recyclability and enhancing the performance and lifetime of materials in order to reduce waste and pollution,” he says. Now a Senior Lecturer in the Department of Materials at Imperial College London, he leads a dynamic research group doing fundamental research in advanced manufacturing and material design.
Vietnam is a developing country, and conditions in the 1980s were difficult. When Dr Pham’s family suffered a financial crisis, there was no safety net. At the age of seven he dropped out of school, and together with his mother, older brother and sister, he went to glean rice from the paddy fields and later to scour landfills for anything of value that could be sold.
He was nine years old when the family’s situation improved enough for one of the children to go to school. As the youngest child, he was offered that privilege. “I needed to wake up early in the morning and often went to the landfills with an empty stomach. I saw that other kids went to school, and I wanted to do that and not go to the landfill,” he recalls.
He rejoined classes with children his own age, which meant catching up more than a year of schooling he had missed. And outside of school, he still went to work, or cooked and cleaned around the house. Even then, he recognised the sacrifice his family was making.
“I could see that my eldest brother and older sister also wanted to go back to school and join their friends, so I knew it was a privilege. In a way, I’m sorry that I didn’t become a teacher to support the children of disadvantaged people in Vietnam. When I retire, I might go back and do that.”
After finishing high school he studied engineering at Hanoi University of Science and Technology, majoring in metallurgy. He adapted and excelled in his studies, finishing with an award for academic achievement. “In addition to perseverance, one thing I learned growing up is to observe and reflect, and I came to love the subject,” he says.
On graduating he won a scholarship to do a Master’s degree in South Korea. “I did not dream of leaving Vietnam, but getting the scholarship was a big moment,” he says. “At the time this was a rare chance for graduates, and most people didn’t get this opportunity.”
It turned out to be a mixed blessing. He could continue studying, however sometimes he was harassed and bullied. “My English was not very good at that time, so I had problems communicating. When people mocked the way I spoke or tried to put me in my place, I pushed back.”
Then he was awarded a further scholarship, to do a PhD at ETH Zurich in Switzerland. When he learnt that his supervisor would be English, he once again doubted his ability to communicate.
“My supervisor noticed that I was very quiet, and when I apologised for my English he just said it was unfair that we had to speak his language rather than Vietnamese,” he recalls. “He really helped me regain my confidence.”
His PhD research involved studying the microstructure of steels, and how crystalline imperfections change the behaviour of steels in safety-critical applications such as nuclear power plants. “We believe that we have to perfect something to make it better, but in materials the opposite can be true: we introduce crystal defects inside materials to make them better, and that idea fascinates me,” he says.
For his post-doctoral work he changed country again, moving to Carnegie Mellon University in the USA to work on metal forming processes, in particular for making car bodies lighter in order to enhance the vehicles’ energy efficiency. He was a guest researcher at the National Institute of Standards and Technology and collaborated closely with major car manufacturers. This experience of the power generation and automobile industries throughout his PhD and postdoc studies brought new perspectives to his work.
“Materials often exhibit different properties in the lab and when they are used in real applications,” he says. “There may be more complex loading conditions, and different behaviour over the long term, and it is important to study these.”
If this sounds more like engineering than science, Dr Pham disagrees. “There are still lots of fundamental questions to answer when you translate materials into applications. This helps us to see their behaviour in a more complete way.”
His next move was to Imperial, where he had the chance to establish a research group in the Department of Materials. “Imperial is very strong in metallurgy, in particular in high performing metallic alloys, with teams covering almost every important topic in metals, so I was keen to apply.”
The work he has pursued at Imperial takes in new applications, but rests on the same fundamental questions about how metals behave. “It’s still trying to understand the best way we can manipulate the microstructure of metals to give new properties, higher performance, and longer life in different applications,” he says.
One focus has been 3D printing of metals. The rapid heating and cooling of metals involved in this process has implications for the properties of the final product. “The atoms don’t have enough time to form the microstructure they would in slower cooling processes, and that affects the metal’s properties.”
Once you understand this relationship between processing history and microstructure, it is possible to close the loop and change the processing to ensure the final product has the desired properties.
“We have to reassure people that components made for high-performance, safety-critical applications are up to the job. And to do that, we need to go beyond their shape and understand what is really happening inside the metals.”
One highlight from his work at Imperial has been the realisation that knowledge of the inner structure of metals could inform how complex 3D printed objects are designed, greatly improving their performance and reliability.
Metals consist of many crystal grains, each orientated in a different direction, forming a resilient polycrystalline microstructure. “As a metallurgist, I know that polygrains give metals better damage tolerance, and allow us to manipulate their behaviour,” Dr Pham explains. “If we could mimic polycrystalline microstructure to create artificial crystals for printed lattice structures, then perhaps we could also manipulate their behaviour at larger scales.”
Following through on this idea has resulted in structures that are lightweight, stronger and much more damage tolerant. This has immense potential in transport applications, for example, helping to build lighter electric vehicles that are both more fuel efficient and have greater range.
The same approach makes it possible to design objects that fail in a predictable way. A helmet, for example, can be built that absorbs the energy of an impact and channels it away from the head, improving the protection it offers. Then, the same principle of predictable failure means that these structures ‘remember’ their original shape and can be restored relatively easily. Applied to car crumple zones, for example, this would make repairs easier and reduce waste.
This ability of objects to morph between shapes can also be applied to very delicate structures. For example, Dr Pham is working with surgeons at the Hammersmith Hospital to produce a more effective catheter for assessing heart function.
“We were able to design a morphing architecture that, in the compacted configuration, occupies a very small space, so that the catheter can easily pass through a blood vessel,” Dr Pham says. “Then, when the tip gets into the heart chamber, it opens up into a specific shape, matching the heart wall, and presents a dense array of electrodes to enhance the signal resolution.” A patent has been filed on this technology, and it will be taken forward by a new spinout company.
And there is more to come from this line of research. “I’m very excited about the possibilities,” Dr Pham says. “We have the potential to make materials, not only with increased performance and energy efficiency, but also that are intelligent and more adaptive to the environment. In that way we can reduce waste and the demands made on natural resources.”
Another project that Dr Pham is looking forward to involves building collaborations in Vietnam on carbon reduction technologies. “Vietnam has made strong commitments to reduce carbon emissions, and now needs to address challenges such as industrial decarbonisation using green hydrogen, batteries, and carbon capture,” he says.
This summer, Dr Pham was one of the organisers of a meeting on possible pathways to net zero in Vietnam, which involved fellow academics from Imperial, the UK Vietnamese Intellectual Society and leaders from science, technology, and industry in Vietnam. Beginning with discussions on the potential of new technologies to catalyse a clean energy transition, the meeting went on to consider possible collaborations that could help bring this transition about. Currently, he is co-chairing a UK-Vietnam Hydrogen Network funded by UK academies, and leading the network’s theme on hydrogen infrastructure.
“Working on the material challenges of low carbon technologies is fascinating from a scientific point of view. But I still vividly remember the pungent smells on landfills, so doing that work with colleagues from Vietnam is always special to me, as it would help me fulfil my childhood dream of improving conditions in my home country,” he says.
Thank you to Dr Minh-Son Pham for sharing his story.
Written by Ian Mundell
Photography by Thomas Angus
Produced by the Department of Materials, Imperial College London
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