Spotlight: Unique Alloy for the Automotive Industry

Hypothetical scenario: A car hurtles toward a tree and swerves to avoid it when the passenger door meets timber and deforms around it. As the driver, you don't want that metal to crumble under the pressure, and its strength (resistance to deformation) depends entirely on the steps that manufacturers took to make it.

In the manufacturing world, safety is only one consideration. Competing with safety is fuel economy. From heated seating to built-in location services, all of the bells and whistles of newer models add to the weight of the car and make it less fuel efficient. When manufacturers add weight in one area, they look to take weight away in others, so the automotive industry is exploring ways to thin out the metal of car parts without compromising the safety of occupants.

Now, an alloy created at the Max Planck Society in Germany and tested by NIST researchers reveals an unusual quality with automotive applications. The blend of iron, manganese, aluminum and carbon is less dense (+1 for fuel economy) and gets stronger the faster you deform it (+1 for safety).

Adding this particular alloy to that previous scenario means that the car door will be strong at 50 kilometers per hour, but it will be even stronger at 100 kilometers per hour. How do we know this?

At the NIST Center for Automotive Lightweighting, our team put sheets of the metal under strain at the fastest rates possible for a lab experiment, aside from an explosion. The researchers tested the trend of the metal’s strength against the rate at which they pulled from either side of their sample.

Also, the researchers used these mappings (above), produced by NIST postdoctoral researcher Jake Benzing with electron backscatter diffraction, to explore the properties of each metallic grain at the microscale when the alloy was formed (1/2) with a treatment at a relatively low temperature for half an hour and (2/2) with a treatment at the same temperature for eight hours (and both treatments yielded positive results). 

Not only did the alloy not disappoint in strength, but it deformed homogenously, meaning that no sections of our hypothetical car door would be weaker than others.

Now, you can get the full breadth of data from these experiments in a package of two published papers:  

• Take a look at the first analysis in Acta Materialia. 
• Get the details in the study, published in Materials Science and Engineering: A.