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June 01, 2019

 
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Engineering Alloys and Advanced Manufacturing

 
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What We Do

The main goal of our Engineering Alloys and Advanced Manufacturing Research Laboratory at the University of Miami is to understand how alloy composition, microstructure and manufacturing route are responsible for the mechanical properties we observe. We use a combination of experimental techniques and computational simulation to achieve this goal, including the utilisation of National Laboratory facilities. Our research is strongly rooted in industrial and government interests and demands, forming collaborations between industry and academia to achieve a common goal. Learn more about our research and areas of study below.

You may also be interested in the other Materials Research Groups within our Department of Mechanical and Aerospace Engineering.

Lab Members

 

Prof. James Coakley

Assistant Professor & Principal Investigator

Dr. James Coakley joined the University of Miami Mechanical and Aerospace Department as an Assistant Professor in 2018. He earned his Ph.D. in Materials Science and Engineering at Imperial College London and completed postdoctoral appointments at Imperial College London and at Oak Ridge National Laboratory. He was awarded a Marie Curie research fellowship, co-hosted between Northwestern University and the University of Cambridge. He is a member of the Oak Ridge National Laboratory review committee, by invitation, and is a symosium organiser for the Minerals, Metals and Materials Society (TMS) conference.

Mr. Junyang Wu

Masters Student

Junyang Yu completed his Bachelors in Materials Science and Engineering at Penn. State University. He is currently completing a Masters in Mechanical Engineering at the University of Miami, including a research project in the area of high ductility beta-titanium alloys.

Research Topics

Manufacturing, Microstructure, Deformation Mechanisms and Material Properties Relationships

High Temperature Alloys

Ni-based superalloys are strengthened by coherent ordered gamma-prime precipitates embedded in a gamma matrix. They are utilised in extreme environments that require excellent high temperature mechanical properties, such as gas-turbine hot sections.

The microstructure of these alloys evolves in-service applications, and there is a concomitant change in mechanical properties. By replicating the engine operating conditions in the laboratory, we can quantify the microstructure evolution and change in material strength. Furthermore, we also perform modelling simulations in order to safely predict a component lifetime while also accelerating materials research and development at a lower cost.

Ni-based superalloy technology is now mature, and their high-temperature mechanical properties are a limiting factor to improving gas-turbine efficiency. Research is ongoing to discover a superior material, including the recently discovered Co-based superalloys.

Titanium Alloys

In general, titanium alloys possess a very high strength-to-weight ratio, corrosion resistance, and excellent high temperature mechanical properties up to about 550 celsius (a higher temperature is obtained by specialized engine alloys). They also possess excellent ballistic resistance, and can be allowed to obtain a very low elastic modulus. With these properties, titanium alloys are utlised in aerospace, chemical, petroleum, biomedical and military industries.

With appropriate alloying, titanium alloys can possess a hexagonal close packed (hcp) microstructure termed alpha, a body centered cubic (bcc) microstructure termed beta, or a combination of both (alpha + beta). Deformation can occur by dislocation slip, twinning induced plasticity (TWIP), or transformation induced plasticity (TRIP via a martensitic transformation). It is this versatility in microstructure and and deformation mechanism design that allows metallurgists to obtain such a broad range of material properties.

Additive Manufacturing

The Johnson & Johnson collaborative laboratory at the University of Miami houses three direct metal laster sintering (DMLS) systems (also known as laser powder bed fusion (LPBF) or selective laser melting (SLM)), as well as advanced powder processing and characterisation facilities.

Direct metal laster sintering is an additive manufacturing/3D printing technique that uses a high power-density to melt and fuse metallic powders together. T process has the ability to fully melt the metal material into a solid three-dimensional part.

The engineering alloys and advanced manufacturing research​ group uses this collaborative facility to explore novel alloys tailored for additive manufacturing production, as well as examining the relationship between manufacturing variables (for example powder feedstock size) to the final microstructure and material properties obtained.

High Strain-Rate Materials Failure

The point of failure is a fundamental determinant of material utility. High velocity material failure is of broad interest and particular importance to the fields of astrophysics, materials engineering and aerospace engineering. High strain-rate deformation is not thoroughly understood, given the challenges of experimentally quantifying material evolution at extremely short time-scales. Recent experiments performed at the Linac Coherent Light Source (LCLS) have quantified the failure mechanisms for the first time, and further information will be presented here once the article has been accepted for publication.

 
 

Laboratories and Facilities

The Departments Flagship Laboratory is the The UM College of Engineering – Johnson & Johnson 3D Printing Center of Excellence Collaborative Laboratory. This 6000 square foot facility houses three selective laser melting (SLM) systems, as well as advanced powder processing and materials characterisation equipment.

The Engineering Alloys and Advanced Manufacturing laboratory complements this facility with further resources, and via collaboration with national laboratories,  industry and university laboratories.

Manufacturing and Processing

  1. A Buehler AM200 arc melter designed for melting samples of up to approx. 200 g at temperatures up to 3500°C.

  2. A ProX DMP 320 SLM and is optimized for applications requiring complex, chemically-pure titanium, stainless steel or nickel super alloy parts.

  3. An EOS M 100 SLM with modular design. 

  4. 3D MicroPrint DMP64 SLM capable of resolution < 15 µm.

  5. Tekna plasma atomiser.

  6. Ball-mill

  7. A suite of furnaces with different atmosphere options

Sample Preparation

1. Struers mounting, grinding, polishing, cutting and ultrasonic resonance equipment for microscopy sample preparation
2. 5-axis wire EDM, Haas VF1 CNC mill and Haas ST-20Y CNC lathe for mechanical testing specimen preparation.
3. Ball-milling

Microscopy and Atom Probe Tomography

  1. The university has a number of SEMs including A Zeiss EVO 60 SEM with EDX.

  2. Atom probe tomography and TEM is performed at other facilities.

Mechanical Testing

We have a 10 kN and 100 kN load rig for room temperature tensile and compression testing, with a variety of grips and extensometry available. Elevated temperature mechanical properties are evaluated elsewhere.

In-situ X-ray and Neutron Scattering

We regularly visit national laboratory facilities to perform in-situ small angle and wide angle x-ray and neutron scattering experiments during thermal and/or mechanical loading.

Integrated Computational Materials Engineering (ICME) Simulations

We apply and develop ICME simulations to accelerate material development at a lower cost, to rationalise experimental observations, and to give component lifetime predictions.

Chemical Composition and Powder Characterisation

  1. LECO gas analysers for O, N, C, and S analysis

  2. Mictotrac particle size analyser

  3. Inductively coupled plasma mass spectrometry