**4. Conclusion**

High entropy alloys (HEAs) possesses superior mechanical, thermal and oxidation properties exceeding that of pure metals. Attributed to the core effects; high mixing entropy, lattice distortion, slow diffusion and cocktail effect. HEAs have outstanding strength is comparable to some metallic glasses and that of structural ceramics attributed to the simple solid solutions they form. Valence electron concentration, CALPHAD and using the thermodynamic and geometry effect are suggested means of discovering the phase HEAs.

High entropy alloys have shown good wear and corrosion resistance with their thermal conductivity lower than that of pure metals. The alloys have remarkable superconductivity and have been reported to be applicable in high temperature and low-density

**149**

provided the original work is properly cited.

2 University of Lagos, Akoka, Nigeria

\*, Patricia Popoola1

1 Tshwane University of Technology, Pretoria, South Africa

\*Address all correspondence to: dadadupeola@gmail.com

3 Council for Scientific and Industrial Research, Gauteng, South Africa

*High Entropy Alloys for Aerospace Applications DOI: http://dx.doi.org/10.5772/intechopen.84982*

alternative.

**Author details**

Modupeola Dada1

refractory for the aero engine components. However, defects have been reported to limit the fatigue resistance of high entropy alloys using arc melting; the most widely used technique of fabricating high entropy alloy until recently. Many techniques have been substituted over the conventional process of manufacturing high entropy alloys; mechanical alloying, sputter deposition, molecular beam epitaxy (MBE), pulse-laser deposition (PLD), atomic layer deposition (ALD) and vapor phase deposition. However, none of these techniques is versatile, flexible and customizable. None use a computeraided design file eliminating the need to change the production line just to make one part. None of the techniques mentioned above is built layer by layer reducing excesses while human production errors are minimal. None have more complex parts produced in shorter time frames and which assures higher product quality because parts developed

are without residual porosity than the laser additive manufacturing technique.

Therefore, there are limitless possibilities in using high entropy alloys fabricated using laser additive manufacturing for aero engine applications. Not only are high entropy alloys similar to nickel-based superalloys currently in use but also a cheaper

© 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,

, Samson Adeosun<sup>2</sup>

and Ntombi Mathe3

### *High Entropy Alloys for Aerospace Applications DOI: http://dx.doi.org/10.5772/intechopen.84982*

refractory for the aero engine components. However, defects have been reported to limit the fatigue resistance of high entropy alloys using arc melting; the most widely used technique of fabricating high entropy alloy until recently. Many techniques have been substituted over the conventional process of manufacturing high entropy alloys; mechanical alloying, sputter deposition, molecular beam epitaxy (MBE), pulse-laser deposition (PLD), atomic layer deposition (ALD) and vapor phase deposition. However, none of these techniques is versatile, flexible and customizable. None use a computeraided design file eliminating the need to change the production line just to make one part. None of the techniques mentioned above is built layer by layer reducing excesses while human production errors are minimal. None have more complex parts produced in shorter time frames and which assures higher product quality because parts developed are without residual porosity than the laser additive manufacturing technique.

Therefore, there are limitless possibilities in using high entropy alloys fabricated using laser additive manufacturing for aero engine applications. Not only are high entropy alloys similar to nickel-based superalloys currently in use but also a cheaper alternative.
