#tohoku university

A new heating method for certain metals could lead to improved earthquake-resistant construction materials.

Tohoku University researchers and colleagues have found an economical way to improve the properties of some ’shape memory’ metals, known for their ability to return to their original shape after being deformed. The method could make way for the mass production of these improved metals for a variety of applications, including earthquake-resistant construction materials.

Most metals are made of a large number of crystals but, in some cases, their properties improve when they are formed of a single crystal. However, single-crystal metals are expensive to produce.

Researchers have developed a cheaper production method that takes advantage of a phenomenon known as ‘abnormal grain growth.’ By using this method, a metal’s multiple 'grains’, or crystals, grow irregularly, some at the expense of others, when it is exposed to heat.

The team’s technique involves several cycles of heating and cooling that results in a single-crystal metal bar 70 centimetres in length and 15 millimetres in diameter. This is very large compared to the sizes of current shape memory alloy bars, making it suitable for building and civil engineering applications, says Toshihiro Omori, the lead researcher in the study.

A research group, utilizing inexpensive elements, has demonstrated the feasibility of synthesizing electrode materials for lithium-ion batteries (LIBs). If explored further, this method could reduce industrial reliance on rare metals such as cobalt and nickel.

Details of their results were published in ACS Applied Energy Materials on April 11, 2022.

Rare metals are widely used because they form a suitable crystal structure for LIBs’ key component—cathode materials. In these materials, lithium is easily and reversibly extracted/inserted.

Scientists have long sought ways to incorporate other inexpensive elements into the crystal structure. Yet, just like only a certain amount of salt dissolves into water, the solubility of other elements is limited.