Physical and mechanical properties of Titanium Essay

Titanium and its alloys possess excellent physical and mechanical properties such as low density, high specific strength, good fatigue properties, excellent corrosion resistance and biocompatibility [1,2]. These are extensively used in aerospace and defence industries due the high specific strength and toughness [3]. In the past decades, titanium alloys have been accepted as standard materials for manufacturing of fittings, valves, pipes and similar equipment in the chemical process industry [1,2]. Moreover, titanium and its alloys have poor wear resistance which restricts its numerous applications in abrasive and erosion environments [1-4]. Beside its mechanical properties deteriorate significantly above 500degreesC, which prevents their use in certain turboprop and other thermal components [3].
The continued development of processing technologies of metal matrix composites (MMCs), now provides a wide range of opportunities for their use in engineering applications, and overcome above drawbacks [5-7]. Because of composite, materials combine the properties of both the reinforcement and matrix. These results a hybrid material with superior properties than the individual one. The beneficial characteristics of the composite materials would have great potential in enhancing the thermal stability and wear performance [7,8]. Recently, several papers have been focused on the development of titanium-ceramic composites by laser sintering techniques [8]. Graphene-oxide, SiC, TiB, TiN, TiB, TiC and canbon nanotubes are the different reinforcements used in titanium matrix [9-16]. In the recent years, considerable amount of research was carried out on titanium matrix composites (TMCs) reinforced with in situ formed ceramic phases using high-energy lasers [13-16]. The composites synthesized using laser showed improved properties due to fine grain size and homogeneously dispersed reinforcing phases. The refinement of the microstructures increases the strength of materials. Grain size and finer reinforcements have profound outcome on strength of the composites. In earlier reported work [17-20] high power laser was used to develop in situ synthesis of TiC reinforced titanium matrix composites. Hamedi et al. [18] used a pulsed NdYAG laser on titanium sheets pre-coated with 300 mum thick graphite layer. In situ formation of TiC particles and dendrites in the titanium matrix improved hardness of alloying layer. Savalani et al. [19] had choosen pure titanium powder and carbon nanotubes as starting material and pre-deposit powders on titanium substrate to form Ti/TiC composite coatings after laser cladding. Carbon nanotubes reacted with titanium and formed fine TiC phase in situ [19,20]. The composites exhibit high hardness and wear resistance [19]. Iravani et al. demonstrated the laser cladding of pre-mixed powders of copper, tin, titanium and diamond on mild steel [21]. However, no study has been reported yet on laser processing of titanium matrix diamond composites. Diamond is the hardest material with high thermal conductivity. We hypothesize that laser melting of diamond and Ti can form TiC and unreacted diamond in Ti matrix which can potentially improve mechanical and tribological properties. Therefore, in the present article, we have investigated the effect of processing technique and diamond compositions on reaction phases in the composites. The microstructure, phase and mechanical behaviour were studied to analyse the effect of reinforcing phases.