A decagonal quasicrystal with point group 10/mmm has been found in Al-14-at.°/o-Fe alloy. Zone-axis patterns of the decagonal phase appearing at the icosahedral positions are reminiscent of the appropriate icosahedral patterns. The symmetry and the angular separation of the zone axes can be obtained from the icosahedral phase by the addition of a mirror plane normal to a fivefold axis. This is supported by the observed diffuse streaking parallel to the tenfold axis. A similar decagonal phase in Al-20-at.°/o-Mn alloy reported by Bendersky can likewise be explained by the addition of mirror planes intersecting a fivefold axis of the icosahedral phase.

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Topology optimization for additive manufacturing has been limited to the design of single-piece components that fit within the printer's build volume. This paper presents a gradient-based multicomponent topology optimization method for structures assembled from components built by powder bed additive manufacturing (MTO-A), which enables the design of multipiece assemblies larger than the printer's build volume. Constraints on component geometry for powder bed additive manufacturing are incorporated in a density-based topology optimization framework, with an additional design field governing the component partitioning. For each component, constraints on the maximum allowable build volume (i.e., length, width, and height) and the elimination of enclosed cavities are imposed during the simultaneous optimization of the overall topology and component partitioning. Numerical results of the minimum compliance designs revealed that manufacturing constraints, previously applied to single-piece topology optimization, can unlock richer design exploration space when applied to multicomponent designs.