Researchers at the Department of Energy's Pacific Northwest National Laboratory knew the titanium alloy made from a low-cost process they had previously pioneered had very good mechanical properties, but they wanted to know how to make it even stronger. Using powerful electron microscopes and a unique atom probe imaging approach they were able to peer deep inside the alloy's nanostructure to see what was happening. Once they understood the nanostructure, they were able to create the strongest titanium alloy ever made.
They note in a paper published in Nature Communications that the material is an excellent candidate for producing lighter vehicle parts, improving vehicle fuel economy and reducing CO2 emissions. This newfound understanding may lead to creation of other high strength alloys.
Much like a medieval blacksmith, researchers knew that they could make this alloy even stronger by heat-treating it. Heating the alloy in a furnace at different temperatures and then plunging it into cold water essentially rearranges the elements at the atomic level in different ways thereby making the resulting material stronger.
The PNNL team knew if they could see the microstructure at the nano-scale they could optimize the heat-treating process to tailor the nanostructure and achieve very high strength.
"We found that if you heat treat it first with a higher temperature before a low temperature heat treatment step, you could create a titanium alloy 10-15% stronger than any commercial titanium alloy currently on the market and that it has roughly double the strength of steel," said Arun Devaraj, a material scientist at PNNL. "This alloy is still more expensive than steel but with its strength-to-cost ratio, it becomes much more affordable with greater potential for lightweight automotive applications," added Vineet Joshi a metallurgist at PNNL.
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