NiAl-Cr-Mo Medium Entropy Alloys: Microstructural Verification, Solidification Considerations, and Sliding Wear...

Area of Science:

• Materials Science
• Metallurgy
• Tribology

Background:

• Nickel-Aluminum (NiAl) based alloys are crucial in high-temperature applications.
• Understanding the influence of alloying elements like Chromium (Cr) and Molybdenum (Mo) on NiAl microstructure and wear is vital for material development.

Purpose of the Study:

• To investigate the microstructural characteristics of NiAl-Cr-Mo systems with varying Cr/Mo ratios.
• To evaluate the sliding wear resistance of these systems and correlate it with their microstructural features.

Main Methods:

• Production of seven NiAl-Cr-Mo alloy compositions with a constant NiAl content and varying Cr-Mo ratios (e.g., 40Cr-0Mo to 0Cr-40Mo).
• Microstructural analysis to identify primary phases, eutectic microconstituents, and intermetallic phases.
• Sliding wear testing to assess wear resistance.

Main Results:

• Microstructural features, including primary, eutectic, and intermetallic phases, were significantly influenced by the Cr/Mo ratio.
• An increasing Molybdenum (Mo) to Chromium (Cr) ratio led to a notable reduction or elimination of the eutectic microconstituent.
• The sliding wear behavior deviated from established laws, indicating a complex interplay of factors.

Conclusions:

• The microstructure of NiAl-Cr-Mo alloys is controllable via the Cr/Mo ratio, impacting solidification phenomena.
• Sliding wear resistance is governed by multiple factors, including oxide formation, intermetallic phases, and the integrity of primary phase interfaces.
• Further research is needed to fully elucidate the complex wear mechanisms in these advanced alloy systems.