NSF-funded reseach: A Fundamental Study of Flow Mechanisms in Nanostructured Al Alloys and Intermetallic Compounds

The objectives of this project are to understand the plastic flow mechanisms for strengthening and plasticity in micro- and macro-scales in ultrafine microstructures, and to design strategies to increase both strength and ductility of ultrafine-grained Al systems processed by HPT. This project combines expertise in metallurgical research on nanocrystalline materials with advanced characterization methods of measurements by the novel nanoindentation technique and state-of-the-art X-ray and electron diffraction analysis.

Strengthening of an ultrafine-grained Al-Li alloy processed by HPT with a precipitation hardening approach

The objectives of this project are two objectives. The first being to improve the mechanical properties, such as toughness and tensile strength, of aluminum 2099. The second is to improve the process by which aluminum 2099 undergoes heat-treatment, making it faster and cheaper. This will be accomplished by subjecting samples to severe plastic deformation by HPT.

We would like to express our special thanks to Smiths High Performance who have helped us with the supply of difficult to source metal samples including titanium alloys, for our Advanced Materials Processing and Analysis Laboratory.

Mechanical response, phase transformation and texture evolution of Titanium Aluminide processed by HPT

The objective of this project is to fully characterize ultrafine-grained titanium aluminide (TiAl) processed by the high-pressure torsion technique. With 20-30 nm grain size, such materials demonstrate very different mechanical properties and plasticity behavior than with conventional microstructures. The extreme high-pressure torsion introduces complexed plastic shear strain. Not only the grain size has been refined, atomic disorder is introduced and large intergranular and residual stresses occur as a function of position within the bulk body. By utilizing Quantum Beam Science, we will perform position resolved maps recording the total scattering in order to evaluate crystallographic phase composition, size-strain broadening, atomic disorder, residual hydrostatic pressure, residual stress, crystallographic texture, orientation correlation and strain partitioning between the two phases by orientation resolved peak intensities, peak positions, peak profile and diffuse scattering. 

Facilities

HPT photo

High-Pressure Torsion (HPT)

Manufacture: Moinsys, Korea

Press unit: 100 ton

Function: High-temperature processing unit

Table-top universal testing machine with miniature sample grips

Manufacture: TestResources, USA

Load: 10kN

Function: Tensile testing

Automated Micro Vickers Hardness Testing Machine

Manufacture: Mitutoyo, Japan

Load: 50gf ~ 2 kgf

Function: Auto focus

Vibratory Polisher

Manufacture: Pace Technologies