High damping capacity of single crystalline iron-palladium alloy exhibiting a weak first-order martensitic transformation

We have investigated the influence of twin boundary properties on the damping behavior of single crystalline Fe-31.2Pd (at%) alloy, which exhibits a weak first-order martensitic transformation. Different static tensile stress was applied by dynamic mechanical analyzer to adjust the twin boundary density and hydrogen was doped to modify the twin boundary mobility. A high damping capacity (tan δ > 0.1) in a wide temperature range from about 140 K to 230 K was observed under a low static stress of about 0.3 MPa. Hydrogen doping further increased the maximum value of the damping capacity by introducing a relaxation tan δ peak. The damping capacity decreased with increasing static stress probably due to the decrease in twin boundary density.