Enhanced strength-ductility synergy of amorphous oxide dispersion strengthened Cu-316L-Mo immiscible alloys fabricated by laser powder bed fusion

Abstract

<p>Bulk immiscible alloys with enhanced mechanical properties face the challenge of achieving high tensile strength and proper ductility. To address this issue, nanoscale amorphous oxides were introduced into Cu-316L-Mo immiscible alloy fabricated by laser powder bed fusion (LPBF). These immiscible alloys are characterized by γ-Fe and Cr12Fe36Mo10 (χ) particles dispersed in ε-Cu matrix, with a large amount of nanoscale Cr-O amorphous oxides wrapped between γ-Fe and χ particles, which we called amorphous oxide dispersion strengthened (AODS) immiscible alloys. The formation mechanism of γ-Fe and χ particles is liquid phase separation (LPS) in Cu-Fe system, and the in-situ amorphous oxides is induced by preferential affinity of Cr/O elements and high cooling rate. Moreover, a simple heat treatment at 600 °C drives Fe-rich precipitates within ε-Cu matrix and Cu-rich precipitates within γ-Fe particles. As a result, the immiscible alloy after treatment exhibits high strength (∼897 MPa) with an enhanced elongation of ∼6.4 %. This is the first time that a large number of in-situ generated nanoscale amorphous oxides have been used to strengthen immiscible alloys in material manufacturing. According to the research in this paper, nanoscale amorphous oxides, in conjunction with nanoscale Fe-rich particles produced by liquid-phase separation, can provide a enhancing strength and ductility for Cu-Fe immiscible alloys. These result may offer a new strengthening method for all alloys with Cr-containing produced by additive manufacturing, that is, enhancing the strength and ductility of alloys by in-situ nanoscale amorphous oxides.</p>