Microstructure refinement of Fe₄₀Ni₄₀B₂₀ alloy in non-equilibrium solidification: possibility of nanostructure formation

Abstract

Microstructure refinement of ternary eutectic Fe₄₀Ni₄₀B₂₀ alloy in undercooling and rapid cooling solidification has been studied. In natural cooling conditions, two kinds of microstructure refinement take place with increasing undercooling. For melts with the same undercooling, the as solidified microstructure refines first and then coarsens with increasing cooling rate. On this basis, repeatable experiments show that the combination of melt undercooling at ∼50 K with Ga–In alloy bath rapid cooling produces very fine eutectic cells (∼5 μm in diameter with the lamellae spacing <100 nm). This indicates that an appropriate initial melt undercooling combined with a proper cooling rate is a potential way to produce a bulk nanostructure in ternary Fe₄₀Ni₄₀B₂₀ alloy.

Keywords:

• Microstructure refinement
• Non-equilibrium
• Eutectic
• Nanostructure

The authors are grateful for the financial support of the Free Research Fund of State Key Lab of Solidification Processing (grant nos. 09-QZ-2008 and 24-TZ-2009), the 111 project (project no. B08040), the Natural Science Foundation of China (grant nos. 51071127 and 50901059), the Huo Yingdong Young Teacher Fund (grant no. 111502) and the National Basic Research Program of China (973 Program) under grant no. 2011CB610403.