Role of scanning speed on the microstructure and mechanical properties of additively manufactured Al2O3‒ZrO2

Abstract

AbstractMelt‐grown Al2O3–ZrO2 eutectic (AZ eutectic) ceramics have attracted extensive attention for harsh environment applications. In this work, AZ eutectic ceramic is additively manufactured via one‐step laser powder bed fusion (LPBF). The role of scanning speed on phase formation, crystallographic characteristics, microstructure evolution, and mechanical properties were systematically investigated. The as‐fabricated specimens are mainly composed of α‐Al2O3 and t‐ZrO2. Lower scanning speeds induced the formation of cellular structures consisting of randomly oriented ZrO2. In contrast, nanometer eutectic lamellar structure with well‐defined multiple crystallographic orientation relationships, for example, {100} Al2O3 || {100} ZrO2 and {0001} Al2O3 || {001} ZrO2, occurred at higher scanning speeds. Both the cell size and lamellar spacing decreased with increasing scanning speed. With the microstructure refinement, the crack propagation mode changes from intergranular to transgranular fracture, leading to progressively enhanced fracture toughness with a maximum value of 7.76 MPa·m1/2. The present work could shed light on tailoring the microstructure of LPBF AZ eutectic ceramic via varying processing parameters.