Effect of Ti addition on the damping and mechanical properties of solid-solution FeCrCoNi alloys

A series of multicomponent (FeCrCoNi)_100−xTi_x alloys with excellent mechanical and damping properties were designed and prepared. After solution treatment at 1327 K, the multicomponent alloys exhibited a face-centered cubic structure, and their microstructures showed typical equiaxed grain characteristics. The effects of different Ti contents on the microstructure, damping properties, and mechanical properties of the alloys were investigated; the strengthening and deformation mechanisms were also explored. The addition of solid-solution Ti atoms increased the number of weak pinning points in the alloy, resulting in significant improvement in the damping properties. The damping property of the FeCrCoNi alloy was expressed in terms of its internal friction (Q^–1) value of 0.032. When the Ti content was 1 (at%), Q^–1 was 0.051. However, further increase in Ti content increased the number of immovable dislocations, resulting in reduced damping properties (Q^–1 =0.0469 and 0.036) when Ti contents were 3 and 5 at% respectively. Tensile property measurements showed that with increasing Ti content, the strength of the alloy improved significantly via solid-solution strengthening, and the alloy exhibited a typical plastic fracture. When the Ti content increased from 0 to 5 at%, the yield strength increased from 217 to 337 MPa, the ultimate tensile strength increased from 592 to 728 MPa, while the elongation decreased from 77.7 % to 57.6 %, respectively. The main processing strengthening mechanism of the FeCrCoNi alloy was dislocation strengthening; the alloy(with 3 at% Ti) exhibited the double influence of dislocation and stack fault, while the alloy (with 5 at% Ti) showed a change in mechanism from dislocation-dominated to stack fault-controlled. It is a promising damping material with a wide range of applications.