Damping Behavior in a Wide Temperature Range of FeMn-Like High Entropy Shape Memory Alloys

In this work, a new class of iron-based high entropy shape memory alloys (HE-SMAs) have been designed, characterized, and optimized. These FeCuNiMnV alloys (FeMn-like) with damping properties at low and high temperatures are developed; a methodology is proposed to demonstrate how to preserve this effect from the memory loss observed on conventional damping alloys. The developed alloys are analyzed using X-ray diffraction, scanning electron microscopy and differential scanning calorimetry. Their damping capacity is investigated using a drop weight test device instrumented with a digital image correlation system for the displacement measurement. It is compared with one of FeMnV, NiTi, CuAlNi, and 1050A alloys at different temperatures. The results show that the damping capacity is interesting over a wide range of operating temperatures. It has been established that the cocktail effect obtained by mixing Cu, Fe, Ni, Mn, and V elements allows for optimizing the damping capacity of the HE-SMAs. In addition, the sluggish diffusion may allow these HE-SMAs to prevent the premature aging that leads to a degradation of the damping behavior notably at high temperature. The variation of the composition of the CuxFeyNizMn20V11 alloys enables the adjustment of the alloying element content by favoring the appearance of the non-thermally activated martensite keeping hence a stable damping behavior from - 40 to 200 degrees C.