Crystallographic orientation manipulation enables wide-temperature-range negative thermal expansion in lightweight AlFe2B2-based alloys

Abstract

The present study demonstrates a remarkable synergy between a wide temperature span of negative thermal expansion (ΔTNTE) and a lightweight character in the Al1-xGexFe2B2 alloys. This is realized by introducing a crystallographic texture in the Al1-xGexFe2B2 alloys using the directional-solidification method. The Al0.9Ge0.1Fe2B2 alloy exhibits a macroscopic NTE coefficient of −16.2 × 10−6 K−1 over a wide temperature range of 211 K, spanning from 120 to 331 K. This represents the largest ΔTNTE among NTE magnetic alloys. Besides, the density of the Al1-xGexFe2B2 alloys is only 5.69 g/cm3, which is among the lowest for NTE magnetic alloys.

Keywords

• Negative thermal expansion
• magnetocaloric alloy
• magnetic phase transition
• AlFe2B2 alloy