Enhanced high temperature mechanical properties and heat resistance of an Al-Cu-Mg-Fe-Ni matrix composite reinforced with in-situ TiB2 particles

Enhancing the high temperature mechanical properties and the thermal stability of aluminum alloys are in urgent demand for the lightweight application scenarios (such as pistons, fan blades, crankshafts) working at elevated temperatures. The fabrication of aluminum matrix composites is a promising solution. In this work, TiB2 nanoparticles were in-situ introduced to a typical heat resistant Al-Cu-Mg-Fe-Ni (Al2618) alloy matrix and subjected to hot extrusion. Microscopically, the extruded TiB2/Al composite exhibited refined and bimodal sized grain structure, which was stable after long-time thermal exposure associated with TiB2 particle banding along the extrusion direction. The TiB2/Al composite showed an evident improvement in high temperature strength as well as the strength retention after long-time thermal exposure up to 300 degrees C, compared to the unreinforced alloy. The strengthening effect was remarkable especially at 200 degrees C with an increase of similar to 20% (60-70 MPa) in tensile strength and strength retention after thermal exposure but without the trade-off of ductility. The effects of TiB2 particles on the temperature-dependent strengthening mechanisms and microstructure evolutions were investigated. This work inspires the design, processing and evaluation of novel high strength and heat resistant particle-reinforced aluminum matrix composites for the potential applications under elevated temperature service conditions. [GRAPHICS] .