Precisely controlling the coefficient of thermal expansion (CTE) of devices or components is strongly desired in rapidly developing modern industries.
The negative thermal expansion (NTE) materials, shrinking with increasing temperature, can be potentially used to compensate for positive thermal expansion (PTE) or to even realize zero thermal expansion by forming composite.
Good mechanical properties and large thermal conductivity are especially demanded for NTE materials in order to design and fabricate composites with high thermal stability and reliability.
Despite many years of effort, materials exhibiting combined good NTE, high thermal and mechanical properties are still rare.
The group led by TONG Peng, Institute of Solid State Physics, Chinese Academy of Sciences, reports the good NTE properties together with high thermal and mechanical properties in Laves phase Hf1-xTaxFe2 compounds.
By modifying the Ta concentration in Lave phase compounds Hf1-xTaxFe2, the researchers achieve an excellent NTE performance in Hf0.87Ta0.13Fe2, a linear CTE (¦ÁL) = -16.3 ppm/K over a large temperature of 105 K (222 K - 327 K).
Besides the good mechanical properties, including high compressive strength (~ 400 MPa), Young¡¯s modulus (220GPa) and hardness (882HV), those compounds have high thermal and electrical conductivities superior to other metallic NTE materials.
The present NTE materials may have wide applications as PTE compensators in the fields of microelectronics, spatial applications and cryogenic engineering.
This work has been published in Acta Materialia with the title ¡°Good comprehensive performance of Laves phase Hf1-xTaxFe2 as negative thermal expansion materials¡±.
Paper link: https://www.sciencedirect.com/science/article/pii/S1359645418307419
Fig. 1. Temperature dependent thermal expansion curve, thermal/electrical conductivities, compressive strength and Young¡¯s modulus. £¨Image By TONG Peng£©