National Tsing Hua University professor of materials science Yeh Jien-wei (葉均蔚), who pioneered research into high-entropy alloys, was given special coverage in the academic journal Nature for his contribution creating the next generation of alloys.
Yeh came up with the idea of high-entropy alloys in 1995, while he was driving through the Hsinchu countryside, and the idea has evolved into a fast-moving field that attracts increasingly more scientists and funding on a global scale, Yeh told a news conference held by the Ministry of Science and Technology last week.
Unlike traditional alloys, which are made by mixing a primary metal with a small amount of other elements, high-entropy alloys consist of four, five or more elements mixed together in roughly equal ratios, he said.
Pure metals have a regular atomic structure with identical layers stacked upon each other and those layers slip past each other easily, whereas mixing a metal with another element with a different atomic size can stop slipping and create a harder alloy, he said.
However, it was believed that if too much of the alloying metal was added, a regular atomic structure might be formed when atoms of the alloying and primary metals arrange themselves in a regular pattern, thereby producing a weak and brittle compound, Yeh said.
“I came up with the idea of mixing similar quantities of four or five elements, which increases the number of ways for different atoms to alternate with each other, thereby creating a disorder, or ‘high entropy,’ that would prevent the formation of a regular atomic structure,” he added.
High-entropy alloys can be lighter and stronger than conventional alloys, while being much more resistant to corrosion, radiation or severe wear, he said.
In 2004, a team led by Yeah created the first high-entropy alloy by mixing five to 10 elements to produce alloys that were considerably harder than stainless steel, and the field of high-entropy alloys began to evolve rapidly after that.
There are more than 300 research facilities around the world that are developing high-entropy alloys, and more than 1,000 academic essays have been published on the subject.
“Alloys with remarkable properties have been created over the past 10 years. An alloy used to make jet engines can resist temperatures up to 1,150oC and improve engine performance by 4 percent. Scientists have also developed alloys that can resist radiation to be used in nuclear power plants, as well as alloys with superconductivity. Maybe we can create a UFO-like spacecraft some day,” he said.
Yeh is dubbed the “father of high-entropy alloys” and the Nature story, which was published last month, details how he revolutionized the field of materials science.
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