Influence of δ Phase Microstructure Evolution on the Dynamic Nano-mechanical Properties of GH4169 Alloy

The dynamic nano-mechanical property–δ phase microstructure relationships of GH4169 alloy (equivalent to the American brand Inconel 718) are investigated in this paper. GH4169 samples were aged at 900 °C for different times to obtain different states of δ microstructures, including short rod shaped, needle shaped, and Widmanstatten structures. Nano-impact method is utilized to explore the local dynamic mechanical properties of GH4169 alloy. The obtained results show that the presence of larger rod shape microstructure and needle-like microstructures correlates with greater levels of dynamic plastic deformation. Furthermore, the occurrence of Widmanstatten microstructure and precipitation free zone results in a significant decrement in dynamic plastic deformation resistance, as evidenced by higher dynamic plastic parameters such as the ratio of rebound velocity to impact velocity (v_out /v_in), the ratio of residual depth to maximum depth (h_r /h_max), and the ratio of impact plastic work to total work (W_p /W_t). Simultaneously, the correlations between local dynamic mechanical mechanism and corresponding δ microstructure are also concluded.