One of the factors limiting the output of today’s power plants is the metal used in steam turbine blades, bearings and seals. These metals tend to soften and elongate well before their melting point. By solving these problems, steam turbines can be used to raise the temperature of anything that converts heat into electricity, resulting in greater efficiency and less waste heat lost.
Researchers at Sandia Labs, Ames National Laboratories, and Iowa State University say they have created a 3D-printable, high-performance superalloy that is both stronger and lighter than the most advanced high-temperature alloys in use today.they published their findings in a journal Applied Materials Today.
Composed of 42% aluminum, 25% titanium, 13% niobium, 8% zirconium, 8% molybdenum, and 4% tantalum, this material is an example of a “multi-element superalloy” or MPES . Most alloys are made primarily from one major element, combined with minor concentrations of other elements to enhance specific properties, whereas multi-primary element alloys contain high concentrations of three or more elements. is included.
According to the research team, a wide variety of these alloys show great promise in many metrics. Strength vs. weight, fracture toughness, corrosion and radiation resistance, wear resistance, etc. However, his MPES subset investigated by this team exhibits high strength in hot conditions.
sandia lab
“MPES has a specific strength of 1.8 to 2.6 GPa-cm3/g, based on the hardness-to-density ratio, which exceeds all known alloys, including intermetallics, conventional titanium aluminides, and refractory MPEA. Strength is 300% better than Inconel 718 based on measured peak hardness. [28] A density of 4.5 GPa and a density of 8.2 g/cm3 gives a ratio of 0.55 GPa-cm3/g. “
It’s also specifically designed to be 3D-printable in powder form, placing it in an “unusual nanoscale microstructure” that the researchers discovered was “unaffected by exposure to temperatures of 800°C.” can do. [1,472 °F] This is significantly hotter than the over 570°C (1,058°F) at which typical coal-based power plants operate.
In fact, the 3D printing process accepted “compositionally isolated, high impurity” powder raw materials. The printer itself mixed the alloy as it melted the constituent metals.
Craig Fritz/Sandia Labs
The researchers say the work signals a readiness to explore a larger class of MPES materials that could soon have interesting potential in the aerospace and energy fields. They said more work on the 3D printing process is needed before these alloys can reliably produce large parts without microcracks, and raw materials include rather expensive metals. It warns that this particular MPES will be difficult to scale up. For widespread use in applications where cost is paramount.
Sandia scientist Andrew Kustas said in a press release: “We show that this material has access to a previously unobtainable combination of high strength, light weight and elasticity at high temperatures. I think it’s due to the manufacturing approach.”
This study is open access in journal Applied Materials Today.
Source: Sandia Labs
