  Twenty-one distinct AlxCoCrFeNi alloys were rapidly prepared by laser
alloying an equiatomic CoCrFeNi substrate with Al powder to create an alloy
library ranging x=0.15-1.32. Variations in crystal structure, microstructure
and mechanical properties were investigated using X-ray diffraction, scanning
electron microscopy, scanning transmission electron microscopy and
nanoindentation. With increasing Al content, the crystal structure transitioned
from a disordered FCC to a mixture of disordered BCC and ordered B2 structures.
While the onset of BCC/B2 formation was consistent with previously reported
cast alloys, the FCC structure was observed at larger Al contents in the laser
processed materials, resulting in a wider two phase regime. The FCC phase was
primarily confined to the BCC/B2 grain boundaries at these high Al contents.
The nanoindentation modulus and hardness of the FCC phase increased with Al
content, while the properties of the BCC/B2 structure were insensitive to
composition. The structure and mechanical properties of the laser-processed
alloys were surprisingly consistent with reported results for cast alloys,
demonstrating the feasibility of applying this high-throughput methodology to
multicomponent alloy design.
