Keywords : MAX phase
The Effect of Aluminum Concentration on The Phase Evolution of The Ternary Ceramics Of (Ti-Al-C) System
Engineering and Technology Journal,
2015, Volume 33, Issue 4, Pages 973-984
In this work it has been tried to introduce this type of new materials as reproducible industrial materials and overtake some production obstacles by exploring on the direction of chemistry structure relation.
In this study composition was prepared from elemental powders (Titanium, Aluminum and carbon black) by using the powder metallurgy techniques, under different concentration due to the change in the Ti to Al concentration. The concentrations are (10% Al-80%Ti-10%C), (20%Al-70%Ti-10%C) and (30%Al-60%Ti-10%C).A compacted sample were formed in cold press using a 30ton followed by heat treatment started from (600˚C, 800˚C, 1200˚C and end in 1400˚C). The effect of Al concentration on phase evolution in the Ti-Al-C system has been investigated and the effects of cold pressing as well as heat treatment have been investigated. X-ray diffraction (XRD) and SEM technique we used for phase evolution. The density and porosity percentage were calculated using Archimedes method, also the micro hardness was measured under that different process.
The XRD, SEM data shows that, by increasing the Al concentration intermediate phases like TiAl3 and/or TiAl appear to be stable instead of the H phase. By raising the temperature, transformations accurse to produce both MAX phase structures in this system Ti2AlC and Ti3AlC2. This production pathway from the intermediate phase to ternary phase is suggested to be the more accepted, and it depends on atomic mobility. No evidence for the direct formation of MAX phases from elemental powders is found which may explain the need of high temperatures to produce such phases since the breaking of bonds is required for the intermediate phase. Finally, the use of pre-heating process decreases the temperature of formation of the MAX phases with the effect of the highest Al concentration.