Alloy Development of Ductile and Strain‐Hardening Fe–Ni‐Based Metallic Glass Composite

Metallic‐glass composites (MGCs) combine the strength and hardness of MGs with the ductility, toughness, and fatigue resistance of crystalline materials. This study focuses on developing Fe‐based in situ dendritic MGCs in the (Fe, Ni) – Mo – B – C system with pseudo‐equilibrium phase distributions. The alloy design strategy involves tailoring the liquid compositional partitioning to allow the formation of a MG phase with the quench rates employed and to control the composition of the primary crystalline phase. The alloy's Fe – Ni ratio is fixed to tailor the elastic “softness” of the dendrites, and the B content is varied to achieve different microstructural length scales and volume fractions of crystalline and glassy phases. Splat quenching is used to perform alloy development and create thin sheets of the MGCs. These were then characterized by X‐ray diffraction, microhardness, and ribbon tensile testing. Compositions with ≥3.5 at.% B formed MGCs with crystalline dendrites and an amorphous phase, showing improved ductility and achieving strain hardening in the thin sheets.