**2. Perspective titanium alloys**

Due to the high chemical affinity of titanium to atmospheric gases, the application of conventional titanium alloys at elevated temperature is limited. Single-phase α alloys can be used up to 600°C. Much higher heat resistance is achieved in intermetallic TiAl(gamma)-based alloys. They exhibit superior specific strength-temperature properties, comparing to classical titanium alloys, steels, and nickel-based superalloys, in the temperature range from 500 to 900°C. Nowadays, TiAl-based alloys are considered as a high-potential material for aircraft engines. The main problems related to their applications are low ductility and the difficulty in processing to form a component. Over the last 30 years, three generations of gamma aluminide titanium alloys have been developed and the basic concept of the fourth generation has been described [9].

Another important feature of titanium alloys is the low value of Young's modulus (E)—from about 100 (for β-phase alloys) to 125 GPa (for α-phase alloys). Low-Young's modulus titanium alloys are considered as valuable biomaterials used for bone implants. It allows to prevent stress shielding, which usually leads to bone resorption and poor bone remodeling, when metal implants are used. The new generation of β-type titanium alloys composed of nontoxic and allergy-free elements, the so-called TNTZ alloys (e.g., Ti–29Nb–13Ta–4.6Zr), is characterized by Young's modulus lower than 90 GPa [10, 11]. TNTZ alloys can exhibit the E value lower than 20 GPa—they are called "gum metals." It was found that the most important role in terms of obtaining the outstanding mechanical properties and the unique deformation behavior plays the oxygen content (stabilizes the bcc crystal structure by controlling the martensitic transformation temperature) [12].

Some of the β-type titanium alloys seem to have potential for even broader range of application due to shape memory effect. Shape memory alloys (SMA), especially Ni-Ti alloys (Nitinols), in recent years, have been mainly applied for biomedical implants and devices. However, due to the risk of Ni allergy and hypersensitivity, their long-term use is limited. The β-type Ti-based SMA have been extensively studied as promising candidates for Ni-free biomedical shape memory alloys [13].

## **3. Advanced material technologies**

Novel aspects of material applications are also related to modern manufacturing and processing technologies. It is worth to note about the grain refinement, which causes high strength increase in metallic materials. Severe plastic deformation (SPD) methods allow to achieve high mechanical properties in conventional titanium alloys. Pure nanocrystalline titanium is characterized by the strength level very close to solutionstrengthened titanium alloys (e.g., Ti-6Al-4V) [14]. Ultrafine-grained titanium alloys exhibit high superplastic deformability. Superplastic forming combining with diffusion bonding (SPF/DB) is a well-established method used in aerospace industry for the production of complex-shaped sheet elements made of titanium alloys [15].

Other developing processing areas are: surface engineering, joining methods (e.g., friction stir welding—FSW), and machining [3, 4]. Highly promising are especially additive manufacturing (AM) methods. In contrast to conventional processes (casting, plastic working, or expensive machining), the AM allows to produce nearnet shape structural parts—minimizing finishing techniques cost (machining) and achieving mechanical properties at least at the level of cast and wrought products. AM of titanium alloys has been used quite quickly to many applications in aerospace and medical industry. Titanium and its alloys are considered as ideal materials for the additive manufacturing industry [16].

**5**

**Author details**

provided the original work is properly cited.

Maciej Motyka\*, Waldemar Ziaja and Jan Sieniawski

\*Address all correspondence to: motyka@prz.edu.pl

*Introductory Chapter: Novel Aspects of Titanium Alloys' Applications*

*DOI: http://dx.doi.org/10.5772/intechopen.83722*

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Department of Materials Science, Faculty of Mechanical Engineering and

Aeronautics, Rzeszow University of Technology, Rzeszow, Poland

*Introductory Chapter: Novel Aspects of Titanium Alloys' Applications DOI: http://dx.doi.org/10.5772/intechopen.83722*

*Titanium Alloys - Novel Aspects of Their Manufacturing and Processing*

Due to the high chemical affinity of titanium to atmospheric gases, the application of conventional titanium alloys at elevated temperature is limited. Single-phase α alloys can be used up to 600°C. Much higher heat resistance is achieved in intermetallic TiAl(gamma)-based alloys. They exhibit superior specific strength-temperature properties, comparing to classical titanium alloys, steels, and nickel-based superalloys, in the temperature range from 500 to 900°C. Nowadays, TiAl-based alloys are considered as a high-potential material for aircraft engines. The main problems related to their applications are low ductility and the difficulty in processing to form a component. Over the last 30 years, three generations of gamma aluminide titanium alloys have been developed and the basic concept of the

Another important feature of titanium alloys is the low value of Young's modulus

Some of the β-type titanium alloys seem to have potential for even broader range of application due to shape memory effect. Shape memory alloys (SMA), especially Ni-Ti alloys (Nitinols), in recent years, have been mainly applied for biomedical implants and devices. However, due to the risk of Ni allergy and hypersensitivity, their long-term use is limited. The β-type Ti-based SMA have been extensively studied as promising candidates for Ni-free biomedical shape memory alloys [13].

Novel aspects of material applications are also related to modern manufacturing and processing technologies. It is worth to note about the grain refinement, which causes high strength increase in metallic materials. Severe plastic deformation (SPD) methods allow to achieve high mechanical properties in conventional titanium alloys. Pure nanocrystalline titanium is characterized by the strength level very close to solutionstrengthened titanium alloys (e.g., Ti-6Al-4V) [14]. Ultrafine-grained titanium alloys exhibit high superplastic deformability. Superplastic forming combining with diffusion bonding (SPF/DB) is a well-established method used in aerospace industry for the production of complex-shaped sheet elements made of titanium alloys [15].

Other developing processing areas are: surface engineering, joining methods (e.g., friction stir welding—FSW), and machining [3, 4]. Highly promising are especially additive manufacturing (AM) methods. In contrast to conventional processes (casting, plastic working, or expensive machining), the AM allows to produce nearnet shape structural parts—minimizing finishing techniques cost (machining) and achieving mechanical properties at least at the level of cast and wrought products. AM of titanium alloys has been used quite quickly to many applications in aerospace and medical industry. Titanium and its alloys are considered as ideal materials for the

(E)—from about 100 (for β-phase alloys) to 125 GPa (for α-phase alloys). Low-Young's modulus titanium alloys are considered as valuable biomaterials used for bone implants. It allows to prevent stress shielding, which usually leads to bone resorption and poor bone remodeling, when metal implants are used. The new generation of β-type titanium alloys composed of nontoxic and allergy-free elements, the so-called TNTZ alloys (e.g., Ti–29Nb–13Ta–4.6Zr), is characterized by Young's modulus lower than 90 GPa [10, 11]. TNTZ alloys can exhibit the E value lower than 20 GPa—they are called "gum metals." It was found that the most important role in terms of obtaining the outstanding mechanical properties and the unique deformation behavior plays the oxygen content (stabilizes the bcc crystal structure

by controlling the martensitic transformation temperature) [12].

**2. Perspective titanium alloys**

fourth generation has been described [9].

**3. Advanced material technologies**

additive manufacturing industry [16].

**4**
