Dual effects of Ru on TCP phase growth and twinning behavior in a fourth-generation single crystal superalloy at 1100°C/150MPa creep condition

Dual effects of Ru on the growth and twinning behavior of topologically close-packed (TCP) phase during steady stage of creep at 1100 °C/150 MPa in a fourth-generation single crystal superalloy was investigated. For the positive aspect, the addition of Ru suppressed the growth of TCP phase by replacing the W element (Main forming-element of TCP phases) in the TCP phase and producing an “inverse partitioning” effect on the W element, which in turn reduced the degree of stress concentration around the TCP phase. For the negative aspect, the addition of Ru inhibited the twinning transition in the TCP phase by increasing the stacking fault energy, thus reducing the plasticity of the TCP phase and increasing the stress concentration around it, which in turn slightly raised the tendency of hole and crack sprouting.