High-throughput assessment of the microstructural stability of segregation-engineered nanocrystalline Al-Ni-Y alloys

TL;DR

This study employs high-throughput combinatorial synthesis and in situ microscopy to identify and analyze thermally stable nanocrystalline Al-Ni-Y alloys, revealing the role of co-segregation in microstructural stability and hardness.

Contribution

It introduces a high-throughput approach combining synthesis and characterization to optimize and understand microstructural stability in nanocrystalline alloys.

Findings

Optimal composition with highest thermal stability identified

Removal of Y correlates with reduced stability at high temperatures

Co-segregation enhances hardness and delays microstructural instability

Abstract

Segregation engineering has emerged as a promising pathway towards designing thermally stable nanocrystalline alloys with enhanced mechanical properties. However, the compositional and processing space for solute stabilized microstructures is vast, thus the application of high-throughput techniques to accelerate optimal material development is increasingly attractive. In this work, combinatorial synthesis is combined with high-throughput characterization techniques to explore microstructural transitions through annealing of a nanocrystalline ternary Al-base alloy containing a transition metal (TM=Ni) and rare earth dopant (RE=Y). A down-selected optimal composition with the highest thermal stability is annealed through in situ transmission electron microscopy, revealing that the removal of the RE species is correlated to a reduction in the microstructural stability at high temperatures as a result of variations in intermetallic phase formation. Results demonstrate the benefits of co-segregation for enhancing mechanical hardness and delaying the onset of microstructural instability.