Thermal expansion of functionally graded and wafer-layered structures produced by laser direct metal deposition

A range of engineering alloys was selected to create two distinct sets of structures. One was functionally graded materials (FGM)—using pairs of these alloys—and the second type was a series of wafer-layered structures using pairs of these alloys in different combinations. The aim of this investigation was to identify unique sets of structures of alloys which provide very different coefficients of thermal expansion (CTE) compared to those of individual elements. The process used to create these structures was laser direct metal deposition (DMD) additive manufacturing technology. The linear thermal expansion coefficients of these samples were measured and the results show that specific sets of FGM and wafer type structures of specific constituent metal alloys can be fabricated by DMD, in which the overall coefficient of thermal expansion of these new structures is significantly different from that of each alloy when measured individually. FGM and wafer type structures of specific constituent metal alloys have lower CTE than those of original alloys.