Fabrication And Properties Of Al/Ti₃SiC₂-Class Composites

With the rapid development of new technologies on aviation, spaceflight and micro-electronics,the request of general properties to Al-matrix is getting higher and higher.Due to have the special properties of both metal and ceramics, MAX compound has became the hotspot of research inland and overseas as the wild phase.This work mainly studies the fabrication and properties of Al/Ti₃SiC₂-class composites.The missions of this work are:l) To fabricate high purity of Ti₃SiC₂ and Ti₂AlC powders. 2) To study the fabrication of (40-80vol.%) Al with Ti₃SiC₂ (or Ti₂AlC) composite bulks by a pressureless calcining technic.3) Using the technologies of XRD, SEM, EDS etc. to character the composition and microstructure of the material and testing the physical properties .The results show that: Using Al (or Sn) as additives can effectively inhibit the generating of TiC phase and other impurities in the synthesizing process of Ti₃SiC₂(or Ti₂AlC). Based on this technique, the nearly pure Ti₃SiC₂ (or Ti₂AlC) products can be reliably obtained, in large scale, by a pressureless calcining technic. Also, the coMPact Al/Ti₃SiC₂ (or Al/Ti₂AlC) composite can be obtained by pressureless sintering the proper ratios of Al and Ti₃SiC₂ (or Ti₂AlC) powders among 650-750℃with 30min heat.Due to the dissolution of Al , there is a small amount of Si dissolution from Ti₃SiC₂ and generated Al₄C₃,Al₄SiC₄ and Al₃Ti compounds surrounding the Ti₃SiC₂ particles. But Ti₂AlC completely decomposed, mainly generated Al₃Ti,TiC compounds.The flexural strength of Al/Ti₃SiC₂ composite fabricated at 750℃for 30min is between 136.77 MPa and 225.53 MPa, at the same time with increasing of Ti₃SiC₂ volume content, the flexural strengh of Al/Ti₃SiC₂ decreased; The elecrtrical resistivity is among 0.1119μΩ·m-0.7344μΩ·m.The composite materials have a relatively low resistivity; And the density of Al/Ti₃SiC₂ is between 2.74 g/cm³ and 2.910 g/cm³.The composite materiala have a lower density. And due to Al binder phase with low hardness and good coordination to the interface deformation,It makes the hardness of composite materials greatly reduced.The flexural strength of Al/Ti₂AlC composite fabricated at the temperature among 650-750℃for 30min is between 69.58 MPa and 291.97 MPa, With increasing of Ti₂AlC volume content, the flexural strengh of Al/ Ti₂AlC decreased, At the same time with increasing of temperature and pressure, the flexural strengh of Al/Ti₂AlC increased. The elecrtrical resistivity is among 0.147μΩ·m-0.8281μΩ·m.The composite materials have a relatively low resistivity; And the density of Al/Ti₂AlC is between 2.5199 g/cm³ and 2.9811 g/cm³.The composite materiala have a lower density.