Manufacturing single crystals of pure nickel via selective laser melting with a flat-top laser beam

Abstract

• Fabrication of single-crystal structure using selective laser melting was studied. • A flat-top profile was utilized without the implementation of single-crystal seeds. • Parametric optimization resulted in planar melt pool formation. • A homogeneous near-{001}<100> texture was achieved in high building heights. • Suppressing strain accumulation was necessary to avoid high-angle grain boundary. The exploration of flat-top laser profile in fabricating a single crystal (SX) structure using selective laser melting (SLM) in pure Ni was investigated. Optimization of the parameters led to the formation of a planar melt pool. A homogeneous near-{001}<100> texture with suppressed high-angle grain boundary (HAGB) in high building heights of >20 mm was achieved without an SX seed. In addition, the planar melt pool suppressed the geometrically necessary dislocation accumulation and prevented strain-induced continuous dynamic recrystallization that could cause HAGB formation. Thus, an SX structure with homogeneous near-{001}<100> texture and suppressed HAGB was successfully achieved without an SX seed.