**3. Development of titanium aluminide composites for aerospace applications**

LENS technique uses high-powered laser to deposit materials and it has been significant in repairing and building of metallic components [74]. Nevertheless, the qualities and mechanical properties of built components are greatly affected by imperfections like porosity, crack cavitation and inhomogeneous microstructure. Composite are of very high demand in aerospace industry because of requests for property combination like high stiffness, fracture toughness, strength, oxidation resistance and lightweight. Moreover, the impetus for composites in aerospace is the ever-increasing demand, thus substitute for metal alloys as weight reduction, cost-saving and fuel efficiency [75]. The aviation industry needs components made with materials with high thermal and mechanical properties at reduced cost [75, 76]. Presently, AM of TiAl is developing, but cracks do emanate due to the integrally brittle nature of the material [77].

phases of α-Ti, Ti3Al and TiN. The intermetallic of TiN/Ti3Al are high oxidation

*Laser Based Additive Manufacturing Technology for Fabrication of Titanium Aluminide-Based…*

An examination of the connection between boron (B) content and microstructural characteristics of TiAl/B (Ti-46.5Al-2.5Cr-2Nb-0.5Y/B) composites produced by SLM was carried out [84]. The grain size reduces as B increases but the HAGBs also rises with B. Owing to grain refinement strengthening system, the highest value of 1610.53 MPa and 5.17% was recorded for compressive strength and strain

The effects of Nb, Ta and Zr had been investigated by Bresler et al. [85], for Ti-

TiAl-based alloys of two molybdenum (Mo) content was fabricated by Jiang et al. [86] through vacuum levitation melting (VLM). Mo addition is understood to refine lamellar size colonies. It also encourages twining capabilities and reduces

Laser metal deposition (LMD) was adopted by Carrullo, Falcón and Borrás [87], to analyzed films produced on Ti48Al2Cr2Nb coating during oxidation through optimization of parameters. The coatings demonstrated high oxidation resistance at 800°C. The layers of oxides formed showed complex microstructure and develop-

Ambient temperature mechanical characteristics were evaluated by Dai et al. [88], for coatings of Ti-Al-Si on the substrate of Ti6Al4V through laser surface alloying. Thermal expansion between coating and substrate resulted in crack formation and propagation. The coating basically consists of Ti5Si3 reinforcement in Ti-Al-phase. Si content increase causes resultant rise in brittle Ti5Si3 which had increased hardness than Ti-Al. The process of high-temperature oxidation resistance of Si in Ti-Al-Si system coatings involves increased refining of oxide grains

An investigated of microstructure carried out by Maliutina et al. [89], on laser cladding of TA6Zr4DE using Ti48Al2Cr2Nb powders. The coatings had γ-TiAl and α2-Ti3Al phases of fully lamellar microstructure. The occurrence of niobium as an

*Primary creep regime and minimum strain rate of binary Ti-44Al and Ti-44Al-5X (X = Nb,Ta, Zr) alloys,*

44Al-5X (X = Nb, Ta, Zr) to examine creep properties (**Figure 8**). All alloying elements mostly improve creep performance substantially and reduce interspacing

resistant with microhardness far above the value of Ti6Al4V.

*DOI: http://dx.doi.org/10.5772/intechopen.85538*

of α2/γ while enhancing stability of microstructure.

ment of consecutive layers on coating.

and boosting the creation of Al2O3.

respectively.

cracks in β phase.

**Figure 8.**

**205**

*tested at 900°C and 100 MPa [85].*

According to Kablov et al. [78], the qualitative improvement of the technical and performance indicators of aviation gas turbine engines (AGTEs) and power plants largely depends on the implementation of new materials with a previously unachieved combination of properties. It was established that alloying intermetallic titanium ortho alloy with gadolinium in the amount of 0.1 at.% results to the rise in strength at room temperatures owing to the realization of the mechanism of dispersion strengthening with finely dispersed gadolinium oxides [78].

A crucible-less technique was adopted by Kartavykh et al. [79] to cast TiAl alloy with composition with composition of Ti-44Al-5Nb-3Cr-1.5Zr (at.%) and highgradient float zone (FZ) re-solidification. Dual phase of γ + α<sup>2</sup> lamellar with small quantities of B2 + γ was observed for the FZ processed alloy. This alloy had high tensile strength which is promoted by Cr accumulation in B2 phase.

A third-generation Ti-43.5Al-4Nb-1Mo-0.1B (TNM) fabricated with casting +HIP was studied by Dahar, Tamirisakandala and Lewandowski [27] to determine the influence of thermo mechanical treated specimen and applied force fracture behavior. Noteworthy alterations of phases were noticed due to the processing.

A coating of TiAl resistant to oxidation was developed by Sienkiewicz et al. [80], for thermal shield structures of material. A coating of titanium-aluminum-silicon system of varying chemical configurations was produced through warm spraying. Silicide of Ti5(Si,Al)3 was observed for two kind of morphologies. Generally, the coating shows attractive cyclic and isothermal resistance.

A complete processing chain develop by Juechter et al. [81], to demonstrated that Ti-45Al-4Nb-C processed by selective electron beam melting (SEBM) could be applied in manufacturing turbocharger wheels. This was made possible by enhanced optimization scan approach coupled with heat treatment.

The microstructures and mechanical properties of Ti6Al4V and Ti45Al7Nb powder mixtures in ratio 1:1 was studied by Wenjun, Chao and Feng [82] using Electron beam selective melting (EBSM) to build samples resulting in Ti22Al3.5Nb2V alloy. Two distinct portions of microstructure were noticed, a dual (α<sup>2</sup> + β) phase and martensite portion. The dual phase region had lower microhardness value compared to the other portions.

The effects of carbon (C) addition was studied by Klein et al. [76], on γ-TiAl based alloys. Generally, C induces more α2-phase formation and reduces βo-phase. However, substantial hardening of γ and α<sup>2</sup> phases occurred with rise in C concentration.

Laser cladding TiN/Ti3Al intermetallic composite coatings have been successfully used to increase the elevated temperature resistance to oxidation and mechanical properties of Ti6Al4V alloy [83]. The clads were largely constituted by *Laser Based Additive Manufacturing Technology for Fabrication of Titanium Aluminide-Based… DOI: http://dx.doi.org/10.5772/intechopen.85538*

phases of α-Ti, Ti3Al and TiN. The intermetallic of TiN/Ti3Al are high oxidation resistant with microhardness far above the value of Ti6Al4V.

An examination of the connection between boron (B) content and microstructural characteristics of TiAl/B (Ti-46.5Al-2.5Cr-2Nb-0.5Y/B) composites produced by SLM was carried out [84]. The grain size reduces as B increases but the HAGBs also rises with B. Owing to grain refinement strengthening system, the highest value of 1610.53 MPa and 5.17% was recorded for compressive strength and strain respectively.

The effects of Nb, Ta and Zr had been investigated by Bresler et al. [85], for Ti-44Al-5X (X = Nb, Ta, Zr) to examine creep properties (**Figure 8**). All alloying elements mostly improve creep performance substantially and reduce interspacing of α2/γ while enhancing stability of microstructure.

TiAl-based alloys of two molybdenum (Mo) content was fabricated by Jiang et al. [86] through vacuum levitation melting (VLM). Mo addition is understood to refine lamellar size colonies. It also encourages twining capabilities and reduces cracks in β phase.

Laser metal deposition (LMD) was adopted by Carrullo, Falcón and Borrás [87], to analyzed films produced on Ti48Al2Cr2Nb coating during oxidation through optimization of parameters. The coatings demonstrated high oxidation resistance at 800°C. The layers of oxides formed showed complex microstructure and development of consecutive layers on coating.

Ambient temperature mechanical characteristics were evaluated by Dai et al. [88], for coatings of Ti-Al-Si on the substrate of Ti6Al4V through laser surface alloying. Thermal expansion between coating and substrate resulted in crack formation and propagation. The coating basically consists of Ti5Si3 reinforcement in Ti-Al-phase. Si content increase causes resultant rise in brittle Ti5Si3 which had increased hardness than Ti-Al. The process of high-temperature oxidation resistance of Si in Ti-Al-Si system coatings involves increased refining of oxide grains and boosting the creation of Al2O3.

An investigated of microstructure carried out by Maliutina et al. [89], on laser cladding of TA6Zr4DE using Ti48Al2Cr2Nb powders. The coatings had γ-TiAl and α2-Ti3Al phases of fully lamellar microstructure. The occurrence of niobium as an

#### **Figure 8.**

**3. Development of titanium aluminide composites for aerospace**

LENS technique uses high-powered laser to deposit materials and it has been significant in repairing and building of metallic components [74]. Nevertheless, the qualities and mechanical properties of built components are greatly affected by imperfections like porosity, crack cavitation and inhomogeneous microstructure. Composite are of very high demand in aerospace industry because of requests for property combination like high stiffness, fracture toughness, strength, oxidation resistance and lightweight. Moreover, the impetus for composites in aerospace is the ever-increasing demand, thus substitute for metal alloys as weight reduction, cost-saving and fuel efficiency [75]. The aviation industry needs components made with materials with high thermal and mechanical properties at reduced cost [75, 76]. Presently, AM of TiAl is developing, but cracks do emanate due to the integrally

According to Kablov et al. [78], the qualitative improvement of the technical and performance indicators of aviation gas turbine engines (AGTEs) and power plants

unachieved combination of properties. It was established that alloying intermetallic titanium ortho alloy with gadolinium in the amount of 0.1 at.% results to the rise in strength at room temperatures owing to the realization of the mechanism of dis-

A crucible-less technique was adopted by Kartavykh et al. [79] to cast TiAl alloy with composition with composition of Ti-44Al-5Nb-3Cr-1.5Zr (at.%) and highgradient float zone (FZ) re-solidification. Dual phase of γ + α<sup>2</sup> lamellar with small quantities of B2 + γ was observed for the FZ processed alloy. This alloy had high

A third-generation Ti-43.5Al-4Nb-1Mo-0.1B (TNM) fabricated with casting +HIP was studied by Dahar, Tamirisakandala and Lewandowski [27] to determine the influence of thermo mechanical treated specimen and applied force fracture behavior. Noteworthy alterations of phases were noticed due to the processing.

A coating of TiAl resistant to oxidation was developed by Sienkiewicz et al. [80], for thermal shield structures of material. A coating of titanium-aluminum-silicon system of varying chemical configurations was produced through warm spraying. Silicide of Ti5(Si,Al)3 was observed for two kind of morphologies. Generally, the

A complete processing chain develop by Juechter et al. [81], to demonstrated that Ti-45Al-4Nb-C processed by selective electron beam melting (SEBM) could be

The microstructures and mechanical properties of Ti6Al4V and Ti45Al7Nb powder mixtures in ratio 1:1 was studied by Wenjun, Chao and Feng [82] using

Ti22Al3.5Nb2V alloy. Two distinct portions of microstructure were noticed, a dual

The effects of carbon (C) addition was studied by Klein et al. [76], on γ-TiAl based alloys. Generally, C induces more α2-phase formation and reduces βo-phase.

applied in manufacturing turbocharger wheels. This was made possible by enhanced optimization scan approach coupled with heat treatment.

Electron beam selective melting (EBSM) to build samples resulting in

(α<sup>2</sup> + β) phase and martensite portion. The dual phase region had lower

However, substantial hardening of γ and α<sup>2</sup> phases occurred with rise in C

Laser cladding TiN/Ti3Al intermetallic composite coatings have been successfully used to increase the elevated temperature resistance to oxidation and mechanical properties of Ti6Al4V alloy [83]. The clads were largely constituted by

largely depends on the implementation of new materials with a previously

persion strengthening with finely dispersed gadolinium oxides [78].

tensile strength which is promoted by Cr accumulation in B2 phase.

coating shows attractive cyclic and isothermal resistance.

microhardness value compared to the other portions.

concentration.

**204**

**applications**

*Aerodynamics*

brittle nature of the material [77].

*Primary creep regime and minimum strain rate of binary Ti-44Al and Ti-44Al-5X (X = Nb,Ta, Zr) alloys, tested at 900°C and 100 MPa [85].*

alloying element restrains the oxygen dispersion making impact in the creation of more favored alumina films.

LENS was employed by Zhang and Bandyopadhyay [90], to deposit Ti6Al4V and Al2O3 powders on Ti6Al4V substrate. For the pure Ti6Al4V, α-laths of Widmanstätten Ti was obtained while Ti6Al4V + Al2O3 parts revealed equiaxed grains with non-melted Al2O3. Microhardness results showed that Al2O3 section possessed the maximum hardness value followed by Ti6Al4V + Al2O3 sections.

Direct laser cladding (DLC) of Ti45Al5Nb0.5Si had been studied by Majumdar et al. [91], to determine the consequence of varying parameters on titanium aluminide. Dual phase α<sup>2</sup> + γ was revealed in DLC Ti45Al5Nb0.5Si alloy. The processing parameters had little effect on the microhardness of the clad. Rise in Si quantity improved the propensity to produce cracks.
