Method makes metallic alloys at low cost using less energy

According to a statement, the breakthrough is expected to change how components used in applications including transport and medical devices are produced.

The research, which appears Materials Today, reports on the first Spark Plasma Sintering (SPS) system with an integrated gas quenching mechanism that is capable of alternating phase compositions and retaining the smallest grain features inside a structured metallic alloy.

SPS is a technique used to fuse fine powders into a dense solid material by placing powder into a mold (or die) and simultaneously applying pulses of electric current and mechanical pressure to it.

By varying SPS cooling rates, it is possible to control the phase and grain sizes in a material, thereby tuning its mechanical properties.

In their study, the team of researchers led by Dr Eberhard Burkel, a Professor of Physics of New Materials, demonstrated that rapidly cooling a material directly after SPS fabrication can produce a material with enhanced hardness, strength and ductility.

The new rapid cooling SPS system is based on a commercially available design, modified to include a series of gas inlet nozzles. After sintering, most SPS systems are left to cool naturally, or are flooded with argon gas. The system blasts nitrogen gas into the chamber at high speeds, rapidly cooling the material.

To demonstrate the utility of the system, Grade 5 Titanium (Ti-6Al-4V) was produced at different cooling rates. The most-rapidly cooled alloy was found to be up to 12 per cent harder than the naturally-cooled alloy, and with an improved ductility up to 34±3 per cent. Ti-6Al-4V is the most common titanium alloy in use worldwide, with applications in the aerospace, biomedical and marine industries.

‘The system will play a major role in the production of novel materials, from metals, alloys, metal matrix composites to micro- and nanostructured semiconductors,’ said first author of the study, Dr Faming Zhang.