ORIGINAL ARTICLE Temperature effects on microstructure and mechanical properties of sintered high-entropy equiatomic Ti 20 V 20 Al 20 Fe 20 Cr 20 alloy for aero-gear application Ayodeji Ebenezer Afolabi 1 & Olawale Popoola 2 & Abimbola P. I. Popoola 1 & Fatai O. Aramide 1,3 & Daniel T. Oloruntoba 3 Received: 17 February 2020 /Accepted: 18 May 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020 Abstract This work presented an upgraded high-entropy alloy by the addition of chromium to the conventional Ti-10V-2Fe-3Al alloy to fabricate equiatomic Ti 20 V 20 Al 20 Fe 20 Cr 20 high-entropy alloy via spark plasma sintering powder processing at different temper- ature of 700 °C, 800 °C, 900 °C, 1000 °C, and 1100 °C respectively under a constant heating rate of 100 °C /min, the pressure of 40 MPa, and holding time of 5 min. The microstructure and phase transformation of the sintered alloyed were studied with a scanning electron microscope equipped with energy dispersive spectroscopy. The constituent phases present in the sintered high- entropy alloy were analyzed by X-ray diffraction and were found to show increased development of body-centered cubic solid solution alloys across the temperature gradients. The mechanical properties over a temperature range of 700 ≤ T °C ≤ 1100 generally show an increase in hardness from 3363 to 8480 MPa, tensile strength from 1097.17 to 2766.58 MPa, and yield strength from793.61 to 2001.13 MPa respectively. The SEM-EDS of Ti 20 V 20 Al 20 Fe 20 Cr 20 equiatomic high-entropy alloys show the existence of a nano-net-like spinodal structure at the optimum temperature of 1100 °C, which are rich in body centered cubic structure. At this elevated temperature, the presence of strong body-centered cubic–forming elements such as Cr, Fe, and Al was established from the corresponding EDS. Ti 20 V 20 Al 20 Fe 20 Cr 20 high-entropy equiatomic alloy has been successfully fabricated by spark plasma sintering. The effects of temperature on microstructural and mechanical properties of the sintered Ti 20 V 20 Al 20 Fe 20 Cr 20 alloy demonstrated a general improvement of the alloys at the elevated region. Keywords High-entropy alloys . Aero-gear . Sintering . Equiatomic . Temperature . Microstructure 1 Introduction The structure and mechanical characteristics of the material are the key determinants of suitability for engineering appli- cations, particularly when the material is stressed by high tem- peratures, excessive mechanical vibrations, or chemical spe- cies. Under these limitations, materials usually fail as phase- out mechanisms, which lead to failure over time. High- property profile content is of great importance in aeronautical space applications, such as landing gear, to support aircraft landing and ground operations. The material thus needs to have good high strength, tiredness, wear, and corrosion and must also be capable of withstanding high-impact strengths due to airframe loads [1]. The designs of conventional alloys, including Al, Fe, Ti, Co and Ni-based alloys, have for a long time been primarily based on the use of one element as the main component and the addition of small elements to boost the properties. Since traditional theories of metallurgy indicate that the use of multi- structural alloys can create some complex structures and com- pounds, which make it difficult to study the microstructure and cause mechanical characteristics to degrade. Such prob- lems make it difficult to align conventional alloys with mod- ern applications [2]. Ti-10V-2Fe-3Al (Ti-10-2-3), which is still susceptible to a tribology problem during application due to certain other * Ayodeji Ebenezer Afolabi ayode86@gmail.com 1 Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria West, Pretoria 0183, South Africa 2 Centre for Energy and Electric Power, Tshwane University of Technology, Pretoria West, Pretoria, South Africa 3 Federal University of Technology Akure, Akure, Ondo State 704, Nigeria The International Journal of Advanced Manufacturing Technology https://doi.org/10.1007/s00170-020-05501-9