Be Brief: Strength

Atomic resolution image of aluminum-zirconium precipitates.
Atomic resolution image of aluminum-zirconium precipitates.
Scanning transmission electron microscope (STEM) mapping of the constituent elements (aluminum and zirconium) in the rod-like precipitate phase and the aluminum matrix. The bright dots in the picture are predominantly zirconium atoms, while the dimmer ones are formed by aluminum atoms.
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Think of making a stronger metal alloy as a bit like making sugar water.

Heat water on the stove (because warmer water allows for more dissolved sugar). Add sugar. Stir until it dissolves. At some point, the water can no longer take more sugar and the sweetener stops dissolving. Precipitation strengthening mixes two different metals instead of sugar and water.

This process has three steps. Heat the metal alloy, which in this case is aluminum-zirconium, at high temperature—not enough that the metals become liquid, but enough to ensure a homogeneous solution. Quench the alloy in water to generate a supersaturated solution. Heat the quenched alloy in the furnace at a temperature lower than that used to create the original solution to force the zirconium to migrate into the precipitate.

Atomic resolution image of aluminum-zirconium precipitates.
Scanning transmission electron microscope (STEM) mapping of the constituent elements (aluminum and zirconium) in the rod-like precipitate phase and the aluminum matrix. The bright dots in the picture are predominantly zirconium atoms; the dimmer ones are formed by aluminum atoms.

Materials Science doctoral candidate Deji Fadayomi, and professors Paul Sanders and Gregory Odegard, are working on these precipitation-strengthening mechanisms in aluminum-based alloys. This atomic-resolution image and elemental maps of precipitates were obtained in aberration-corrected scanning transmission electron microscope (AC-STEM) at Michigan Tech’s Applied Chemical and Morphological Analysis Laboratory (ACMAL) to better understand alloy behavior at an atomic level.

Michigan Technological University is a public research university founded in 1885 in Houghton, Michigan, and is home to more than 7,000 students from 55 countries around the world. Consistently ranked among the best universities in the country for return on investment, the University offers more than 125 undergraduate and graduate degree programs in science and technology, engineering, computing, forestry, business and economics, health professions, humanities, mathematics, social sciences, and the arts. The rural campus is situated just miles from Lake Superior in Michigan's Upper Peninsula, offering year-round opportunities for outdoor adventure.

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