Superior zero thermal expansion dual-phase alloy via boron-migration mediated solid-state reaction

Rapid progress in modern technologies demands zero thermal expansion (ZTE) materials with multi-property profiles to withstand harsh service conditions. Thus far, the majority of documented ZTE materials have shortcomings in different aspects that limit their practical utilization. Here, we report on a superior isotropic ZTE alloy with collective properties regarding wide operating temperature windows, high strength-stiffness, and cyclic thermal stability. A boron-migration-mediated solid-state reaction (BMSR) constructs a salient plum pudding structure in a dual-phase Er-Fe-B alloy, where the precursor ErFe10 phase reacts with the migrated boron and transforms into the target Er2Fe14B (pudding) and alpha-Fe phases (plum). The formation of such microstructure helps to eliminate apparent crystallographic texture, tailor and form isotropic ZTE, and simultaneously enhance the strength and toughness of the alloy. These findings suggest a promising design paradigm for comprehensive performance ZTE alloys. Zero thermal expansion (ZTE) alloys with multi-properties are important for high-precision applications, but scarce. Here the authors incorporate a boron-migration-mediated solid-state reaction to construct a dual-phase ZTE alloy with enhanced mechanical properties and cyclic thermal stabilities.

Automated summary

The study presents a new type of ZTE alloy with wide operating temperature range, high strength-stiffness, and cyclic thermal stability. The alloy, constructed through boron-migration-mediated solid-state reaction, exhibits a superior dual-phase structure and provides a promising design paradigm for comprehensive performance ZTE alloys.