Researchers, including those of Indian-origin, have developed a low-cost and lightweight titanium alloy, which is the strongest ever made and may help build lighter vehicles that use less fuel. The improved titanium alloy - stronger than any commercial titanium alloy currently on the market - gets its strength from the novel way atoms are arranged to form a special nanostructure.
For the first time, researchers from Pacific Northwest National Laboratory (PNNL) in the US have been able to see this alignment and then manipulate it to make the strongest titanium alloy ever developed, and with a lower cost process.
The material is an excellent candidate for producing lighter vehicle parts, and this newfound understanding may lead to creation of other high strength alloys, researchers said.
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.
Researchers knew if they could see the microstructure at the nano-scale they could optimise 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 per cent stronger than any commercial titanium alloy currently on the market and that it has roughly double the strength of steel,” said Arun Devaraj from 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,” said Vineet Joshi from PNNL.
Researchers used electron microscopy to zoom in to the alloy at the hundreds of nanometres scale - about 1,000th the width of an average human hair. Then they zoomed in even further to see how the individual atoms are arranged in 3-D using an atom probe tomography system.
By using such extensive microscopy methods, researchers discovered that by the optimised heat treating process, they created micron sized and nanosized precipitate regions - known as the alpha phase, in a matrix called the beta phase - each with high concentrations of certain elements.
When the strength was measured by pulling or applying tension and stretching it until it failed, the treated material achieved a 10-15 per cent increase in strength which is significant, especially considering the low cost of the production process, researchers said. The findings were published in the journal Nature Communications.