Mechanical characteristics of laser-deposited sandwich structures and quasi-homogeneous alloys of Fe-Cu system

• A digital image correlation method emphasized a mismatch between strain and stress concentrators in major cases of Fe-Cu laser-deposited materials. • 50 wt.% – 50 wt.% Fe-Cu alloys showed better mechanical characteristics than 25 wt.% – 75 wt.% materials and sandwich structures. • The existence of δ-ferrite in UNS C61800-based non-gradient Fe-Cu alloys slowed the grain growth and increased the mechanical strength. The laser metal deposition approach implements a unique opportunity for controlling the fabrication of functionally graded and sandwich structures from different metal powders for artificial physical properties management. In this study, the quasi-homogeneous alloys were fabricated by the simultaneous feed of bronze and steel powders from different feeders of the LMD installation and the gradient structures by alternating deposition of the materials. The resulting alloys consisted of 50 wt.% - 50 wt.% and 25 wt.% - 75 wt.% non-gradient bronze-steel parts and sandwich structures of alternating 250-μm-height steel and bronze layers. The alloy based on aluminum bronze demonstrated the highest ultimate tensile strength (838.6 MPa). Its yield stress amounted to 665 MPa, strain-to-fracture – 0.035, Poisson’s ratio – 0.23, and modulus of resilience – 1.03 MJ/m 3 . A digital image correlation approach was applied to study the character of major strain distribution in the fabricated specimens and localizations of strain concentrators and compare them with all specimens’ failure areas. Fractography analysis showed a predominantly brittle character of failure. Investigated materials are expected to be applied as interface regions of Fe-Cu system functionally graded structures.