Enhanced negative thermal expansion of boron-doped Fe43Mn28Ga28.97B0.03 alloy

Abstract Enhanced negative thermal expansion (NTE) properties are achieved by introducing a little amount of boron in the Fe43Mn28Ga28.97B0.03 alloy. As a result, this alloy shows a giant NTE coefficient of αl = −79.7 × 10−6 K−1 in a wide temperature range from 277 K to 136 K. Compared to the NTE characteristics in Fe43Mn28Ga29, the NTE operation temperature window has expanded by 74% with the corresponding coefficient of thermal expansion increased by 57% within the NTE temperature window for the boron-doped Fe43Mn28Ga28.97B0.03. In-situ synchrotron high-energy X-ray diffraction results suggest that by boron substitution, the large unit cell volume change across martensitic transformation and the wide phase transition temperature interval are responsible for the pronounced NTE behavior in Fe43Mn28Ga28.97B0.03. Moreover, for the Fe43Mn28Ga28.97B0.03 NTE material, the compressive strength and strain are significantly improved compared with that of Fe43Mn28Ga29. The present study indicates that Fe43Mn28Ga28.97B0.03 with enhanced NTE across martensitic transformation may be used for practical application as thermal-expansion compensators.