Inconel 625 is a nickel-based alloy that is mainly used in high-temperature applications. Inconel 625 exhibits an unstable plastic flow at elevated temperatures characterized by serrated yielding, well-known as the Portevin-Le Chatelier effect. The evaluation of the mechanical properties of Inconel 625 at high temperatures is the aim of this work. The tensile tests were executed in temperatures ranging from room temperature to 1000 °C with strain rates of 2 × 10⁻⁴ to 2 × 10⁻³ s⁻¹. The creep tests were executed in the temperature range of 600–700 °C and in the stress range of 500–600 MPa in a constant load mode. The optical and scanning electron microscopes were used for surface fracture observation. In the curves obtained at 200–700 °C the serrated stress-strain behavior was observed, which was related to the dynamic strain aging effect. The yield strength and the elongation values show anomalous behavior as a function of the test temperature. An intergranular cracking was observed for a specimen tensile tested at 500 °C that can be attributed to the decohesion of the carbides along the grain boundaries. The fracture surface of the specimen tensile tested at 700 °C showed the predominance of transgranular cracking with tear dimples with a parabolic shape.

Aluminum alloys have low specific weight, relatively high strength and high corrosion resistance and are used in many applications. Aluminum Alloy 2024 is widely used for aircraft fuselage structures, owing to its mechanical properties. In this investigation, Aluminum Alloy 2024 was given solid solution treatments at 495, 505, and 515°C followed by quenching in water. It was then artificially aged at 190 and 208°C. Subsequently, hardness measurements, tensile tests as well as impact and fatigue tests were carried out on the heat treated alloys to determine the mechanical properties. The tensile and hardness tests revealed similar mechanical properties for specimens of this alloy that were given the three solid solution treatments. Aluminum Alloy 2024 specimens that were solid solution treated at 515°C and artificially aged at 208°C for 2h exhibited the highest yield and tensile strength. In general, the increase in strength was accompanied by a decrease in ductility. Cyclic fatigue studies were conducted with symmetric tension-compression stresses at room temperature, using a bending-rotation test machine. The alloy solution heat treated at 515°C and aged at 208°C/2h was fatigue tested at constant frequency. The relation between stress amplitude and cycles to failure was established, enabling the fatigue strength to be predicted at more than 7.8x10⁶ cycles, with maximum stress of 110.23 MPa. The fracture surfaces of specimens that failed after fewer cycles showed mainly precipitates and micro voids, whereas specimens that fractured after a higher number of cycles indicated that cracks initiated at the surface. The high cycle fatigue fracture surfaces revealed pores that could be due to precipitates from the matrix.