Cu-based shape memory alloys (SMAs) and among these copper–zinc (Cu–Zn), copper–aluminum (Cu–Al), and copper–tin (Cu–Sn) alloys both with and without ternary additions have shown potential due to their good shape recovery, ease of fabrication, excellent conductivity of heat and electricity. However, their applications are still limited because of the shortcomings of thermal stability, brittleness, and mechanical strength, which are closely related with microstructural characteristic of Cu-based SMAs, such as coarse grain sizes, high elastic anisotropies, and the congregation of secondary phases or impurities along the grain boundaries. Efforts are being made to overcome these drawbacks with proper ternary additions, adopting alternative processing routes and also optimizing the heat treatment cycles. The present article will deal with the current status of research and commercialization of Cu-based SMAs and dwell upon the future directions in which research should be targeted and future prospects of converting the research into components for commercial use.

A look into Cu-based shape memory alloys: Present scenario and future prospects

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Reconciling viability and cost-effective shape memory alloy options – A review of copper and iron based shape memory metallic systems

Influence of quaternary alloying additions on transformation temperatures and shape memory properties of Cu–Al–Mn shape memory alloy

Dielectric properties and thermal behavior of electrolytic manganese anode mud in microwave field.

Pilot-scale study on enhanced carbothermal reduction of low-grade pyrolusite using microwave heating

Influence of aluminum and manganese concentration on the shape memory characteristics of Cu–Al–Mn shape memory alloys

Cu–Al–Mn shape memory alloys in the range of 10–15 wt.% of aluminum and 0–10 wt.% of manganese, exhibiting β-phase at high temperatures and manifesting shape memory effect upon quenching to lower temperatures, were prepared through ingot metallurgy. The damping behavior of the alloys was studied using a dynamic mechanical analyzer. The damping capacity of the alloys increases with an increase in the aluminum content when the Cu/Mn ratio or amount of manganese is maintained constant. The damping capacity of the alloys decreases with an increase in the manganese content when the Cu/Al ratio or the amount of aluminum is maintained constant. The alloys exhibit an internal friction peak in the transition zone and that all of them exhibit higher damping capacity in the martensitic condition compared with that in the austenitic condition. While ageing of the alloys at 300 °C increases the transformation temperatures of the alloys, there is a reduction in the damping capacity of the alloys due to the formation of precipitates. The alloys aged at 500 °C do not exhibit the austenite to martensite transformation due to the formation of precipitates rich in aluminum and therefore exhibit very poor damping capacity.

Effect of composition and ageing on damping characteristics of Cu–Al–Mn shape memory alloys

Cu–Al–Mn shape memory alloys with 10–14.5 wt.% of Al and 0–10 wt.% of Mn, were chosen for the present study. The transformation temperatures, shape memory effect and superelasticity of these alloys are highly sensitive to variations in composition. The influence of composition on these properties has been studied by differential scanning calorimetry, bend and tensile test. It is found that with the increase in the amount of aluminum the morphology of martensite and its transformation temperatures change. On the other hand, an increase in the amount of manganese stabilizes martensite and enhances the superelasticity of the alloys.

Effect of alloying on microstructure and shape memory characteristics of Cu–Al–Mn shape memory alloys

Cu-12.5 wt.% Al-5 wt.% Mn-(0.05 to 0.2) wt.% B alloys were prepared by ingot metallurgy. The Aluminum and Manganese contents of the alloys were maintained constant, while that of Boron was varied. The alloys were then characterized by subjecting them to compositional analysis, Differential Scanning Caloriemeter and microstructural examination. The shape memory effect and superelasticity of the alloys were determined by bend and tensile tests on the alloy specimens. The investigation reveals that Boron acts as a good grain refiner, resulting in a reduction of about 80% in grain size. The addition of Boron also increases the transformation temperatures by ~ 10oC, while at the same time decreasing the strain recovery by shape memory effect by 4%, and that by superelasticity by ~ 2%.

U.S. Mallik

Papers

Influence of aluminum and manganese concentration on the shape memory characteristics of Cu–Al–Mn shape memory alloys

Effect of composition and ageing on damping characteristics of Cu–Al–Mn shape memory alloys

Influence of quaternary alloying additions on transformation temperatures and shape memory properties of Cu–Al–Mn shape memory alloy

Effect of alloying on microstructure and shape memory characteristics of Cu–Al–Mn shape memory alloys

Effect of Grain Refinement on Shape Memory Properties of Cu-Al-Mn SMAs