2, George Mason University, Fairfax, Virginia, United States
Advanced alloy materials are frequently utilized in applications comprising extreme conditions such as high temperatures or corrosive materials. Nickel chromium based alloys are one such group which is commonly used in industries including jet engine manufacturing, thermal and nuclear power generation, and petroleum engineering, and thus it is crucial to learn how reliably they operate at various scales and in different conditions. There is broad interest in further understanding the mechanical behaviors and reliability of these advanced alloys in settings which more closely mimic those in which they are applied, particularly pertaining to how they are affected at the nano and microscales. This work focuses on the experimental investigation of one such alloy, Inconel 718, which has been fabricated by means of additive manufacturing, and the dependence of its mechanical properties on temperatures ranging from – 200 °C up to 800 °C. Advanced nanoindentation methods are used to characterize mechanical and tribological properties, including tribological responses, creep behaviors, and the variation of cracking thresholds for the determination of fracture toughness. Previous work has shown that mechanical properties in such alloys can be altered by variation of their environment, and it is reported that for large changes in temperature there are noticeable effects in the basic mechanical properties such as hardness and elastic modulus, which was seen to decrease by nearly 30 % at increased temperature, as well as more vital qualities like fracturing behavior. It was concluded that the fracture toughness of additively manufactured Inconel 718 at room temperature is approximately 70 MPa-m1/2, and the cracking threshold load is variable and is dependent on the material temperature.