Powder Metallurgy Processing to Enhance Superelasticity and Shape Memory in Polycrystalline Cu-Al-Ni Alloys:...

Area of Science:

• Materials Science
• Metallurgy

Background:

• Shape memory alloys (SMAs) are crucial functional materials with diverse applications.
• Developing SMAs via additive manufacturing (AM) is of global interest, but challenges exist in achieving optimal microstructures.
• Cu-Al-based SMAs, particularly in polycrystalline form, are prone to brittleness due to high elastic anisotropy.

Purpose of the Study:

• To develop a powder metallurgy route for producing a Cu-Al-Ni shape memory alloy with improved functional properties.
• To characterize the microstructure and its influence on the functional behavior of the processed SMA.
• To demonstrate the potential of this powder metallurgy approach as a reference for AM techniques.

Main Methods:

• Gas atomization of a pre-alloyed melt to produce powders.
• Compaction of powders using hot isostatic pressing.
• Hot rolling and subsequent thermal treatments.
• Microstructural characterization using electron microscopy.
• Evaluation of thermomechanical functional properties (superelasticity and shape memory).

Main Results:

• A specific [001] texture in the rolling direction was achieved, enhancing functional behavior.
• Martensitic transformation temperatures increased by approximately 40 °C, with controlled and reproducible results.
• Fully recoverable superelastic behavior of 4.5% in tension and ±5% shape memory recovery in bending were demonstrated over multiple cycles.
• Enhanced mechanical and functional properties were observed in the polycrystalline Cu-Al-Ni SMA.

Conclusions:

• The developed powder metallurgy methodology successfully enhances the properties of polycrystalline Cu-Al-Ni SMAs.
• The achieved microstructure and properties provide a valuable reference for advancing AM techniques for SMA production.
• This work paves the way for improved manufacturing of SMAs using additive manufacturing technologies.