The Effect Of Titanium On The Microstructure And Mechanical Properties Of Carbon Nanotube-reinforced Aluminum Matrix Composites

With the development of society,traditional metal materials are more and more difficult to satisfy the various demands in properties proposed by some industrials.Among the metal matrix composites system,owing to the light and high strength,aluminum matrix composites reinforced with carbon nanotubes?CNT/Al?have acquired irreplaceable advantages and broad application prospect in aerospace as well as transportation fields.Thus,developing high-performance CNT/Al composites becomes one of the research hotspots in recent years.However,challenges as achieving uniform CNT dispersion and strong CNT-Al interfacial bonding are still the barriers of fabricating the CNT/Al composites.Related theoretical knowledges and practical undiscovered novel methods of fabrication need to be further studied and improved.In the current study,two variables which respectively are the particle size of titanium?Ti?and the Ti addition were set.The surface morphology,the damages of CNTs during the preparation,the microstructure and mechanical properties of the composite powders and extruded composites were characterized by corresponding characteriztion.The analyzed results were as followed:high energy ball milling as an effective method to disperse the CNTs into the Al matrix,but simultaneously cause some damages to CNTs.The addition of Ti greatly shared the burden of CNTs dispersion.After the sintering and hot extrusion,the extruded composites formed a hybrid structure that the TiAl₃ layers were sandwiched between the Al-Ti interfaces.This TiAl₃ layers in-situ formed around the Ti can wrap the CNTs in place,which improve the interface bonding and contributes to the enhanced strength.Thus,with nano Ti and 1?m Ti added,both the composites obtain enough enhancements in tensile strength?241MPa and 221MPa?.And,adding the Ti particle with 1?m can greatly exploit the above strengthening effect and achieve the best tensile strength?216MPa?.Meanwhile,as for the Ti addition,the 7vol%Ti addition was proved to have the best tensile strength?221MPa?due to that composites balance the brittleness effect and the strength effect of the added second phases.