Laser-induced Self-propagating Reaction Synthesis Of Ti-Fe System Alloys

The mechanical property improving technology of Titanium alloys is always being the focus of the Ti fields around the world. Amorphous alloy made by rapid cooling can strengthen Ti alloy, but lower the ductility and restrict its application. So, a new method to solve the problems about the balance of strength and ductility is needed. Noticing that the monotectic alloy has both the high strength and the excellent plasticity of eutectic alloy owed to the existence of ductile preeutectic phase, a brand new way to produce materials with excellent mechanical properties was developed here.Based on negative enthalpy of mixing between Ti and Fe components of eutectic forming alloy systems and the technology mentioned above, a novel technique to fabricate Ti-Fe system eutectic alloys using Laser-induced Self-propagating Reaction Synthesis (LSRS) was developed . With the help of X-ray Diffractometer (XRD) and Scanning Electron Microscope (SEM) and other modern mechanical testing equipments, complicated factor was discussed which influence the microstructure and property such as weight ratio of reactants and the microstructure-evolution process of the Ti-Fe eutectic alloy was researched, too.From the results, we can conclude that the products of LSRS Ti-Fe binary alloys changed from β-Ti solid solution +(β-Ti + TiFe) eutectic alloy, then (β-Ti + TiFe) eutectic alloy to TiFe intermetallics + (β-Ti + TiFe), as Fe content rising. A high-temperature metastable phase Ti₂Fe was found at the interface of eutectic cluster in products because of the enrichment of oxygen. With increasing of the Fe content, the porosity curve varied as a "V" type, the lower-most point correspond to eutectic point; and the mircohardness curve show a gradual rising tendency; The excellent compressive property alloy is Ti_70.5Fe_29.5 which exhibits a high ultimate compressive strength of 1796 MPa and 10% plastic strain.Co content exist in Ti-Fe eutectic alloy as solute within Co content 12%. With increasing of the Co content, the porosity curve and the mircohardness curve both rising. Co addition made alloy system offset left to eutectic point. The compressive strength was increased because of Co addition, but the plastic strain was reduced.The same with Co addition, Ni also soluted in Ti-Fe eutectic alloy, but has a smaller atomic radius. Ti-Fe-Ni alloys were constituted by body-centred cubic β-Ti solid solution, simple cubic TiFe and face-centred cubic Ti₂Fe intermetallic compounds. Low melting point,...