Microstructure-Micromechanics Relationships of Additive Manufactured Components and Dissimilar Welds through Neutron Scattering

GRCop-84, a copper alloy developed by NASA Glenn Research Center with the starting At% Cu-8 Cr-4 Nb, has a copper matrix with a fine intermetallic dispersion of Cr2Nb (cubic Laves phase C15). The alloy is being developed to be used in reusable launch vehicles and has excellent high temperature properties such as tensile strength, thermal conductivity, and creep resistance. GRCop-84 is a high-heat flux application alloy that requires rapid cooling in fabrication to form the desired microstructure. Typically this is achieved by gas atomization from an alloyed melt and followed by powder processing techniques. Recently, it has been used with Selective Laser Melting (SLM) a powder-bed based Additive Manufacturing (AM) technique with success. The time, cost, and achievable geometries are better than those of traditional manufacturing. After heat treatment and Hot Isostatic Pressing (HIP), porosity is reduced and density increases, which results in properties equal to or better than those of traditional. Additive Manufacturing has developed rapidly in recent years making it difficult for sufficient comprehensive research to support it, particularly in metal additive. Additionally, only in recent years have we seen parts made by AM meet rigorous engineering requirements for in-service use. GRCop-84 has shown great adaptability with AM with little adjustment from primary build requirements needed for high survivability rates. The primary factor of survivability with AM is plastic deformation following the first cooling phase after the part has been fully formed which is the result of excess residual stress built up over time. This is usually mitigated by a heat treatment following the print, but the final part must first make it to that stage

Industry Sponsor: NASA

Faculty: Claudia Rawn (UTK)

Graduate Students: Robert Minneci, Jared Floyd

Industry Contact: Terri Tramel