Synthesis & Mechanical Properties of Hetero-Structured Immiscible FeCr-Mg Composites Via Liquid Meta
As the number of international conferences and publications has increased in recent years, heterogeneous structured (HS) composite has recently attracted extensive attention from the material community. HS materials have a wide variety of microstructures, including heterogeneous lamella structures, gradient structures, dual-phase structures, harmonic structures, and metal matrix composite. A wide variety of structures have common characteristics, all of which consist of hard material and soft material with dramatically different flow stress or strength. Recently, Kato-group announced the novel metallic porous and metallic composite fabrication method using a liquid metal dealloying (LMD) technique. The effect of dealloying steps; selective dissolution and self-assembly of the element formed a unique microstructure with a bi-continuous state. Furthermore, many types of research demonstrated that these bi-continuous materials have suggested extraordinary properties can be obtained by forming different structures from the noble microstructure.
In this study, we tried to fabricate heterostructure composite by liquid metal dealloying system and to identify deformation behavior during the tensile test. As shown in Fig 1. (a), the dealloying system is based on the mixing enthalpy relationship. When Precursor (Fe40Cr10Ni50) alloy is immersed in the Mg liquid melt as shown in Fig. 1. (a), FeCr does not respond with Mg (positive mixing enthalpy), but the element Ni reacted with Mg, so eventually develop a composite of FeCr (Hard) – Mg (Soft) having dramatically different mechanical strength. Fig.1. (b) show microstructure after liquid metal dealloying and it can confirm that the microstructure consists of the ligament (FeCr) and melt (Mg). Fig.1.(c) shows the mechanical properties of the present composite and the mechanical properties predicted by the rule of mixture (ROM). We found that the mechanical properties of the present composite exhibited higher yield strength and elongation compared to the same contents of FeCr and Mg calculated by ROM. We would like to interpret this improvement in mechanical properties through the association of dislocation and interfaces.