Effect of Al Content on Microstructure, Microhardness and Corrosion Resistance of Spark Plasma Sintered TiCuNiSi-Al High Entropy Alloy

Basiru Philip Aramide, Mechanical and Mechatronics Engineering Department, Tshwane University of Technology, Pretoria, South AfricaFollow
Tamba Jamiru, Mechanical and Mechatronics Engineering Department, Tshwane University of Technology, Pretoria, South Africa
Taoreed Adesola Adegbola, Mechanical and Mechatronics Engineering Department, Tshwane University of Technology, Pretoria, South Africa
Thomas Ayorinde, Mechanical and Mechatronics Engineering Department, Tshwane University of Technology, Pretoria, South Africa
Fatai Olufemi Aramide, Metallurgical and Materials Engineering Department, Federal University of Technology, Akure, Ondo State, Nigeria
Abimbola Patricia Idowu Popoola, Chemical, Metallurgical and Materials Engineering Department, Tshwane University of Technology, Pretoria, South Africa

Keywords

High-entropy alloys, Aluminum addition, Spark plasma sintering, Microstructure evolution, Microhardness, Corrosion behavior

Document Type

Article

Abstract

Aluminum-based high-entropy alloys have been of interest owing to their potential for improved mechanical strength and corrosion resistance. In this research, TiCuNiSi_xAl high-entropy alloys (x = 0.5–1.7 at.%) were synthesized using spark plasma sintering at a temperature of 600 °C and a pressure of 40 MPa to examine the effects of incremental aluminum addition on the densification behavior, microstructure, microhardness, and corrosion resistance in 0.5 M H₂SO₄ solution. With the increase in Al content, there was an acceleration of the transition from porous, weakly bonded microstructures to more compact multiphase microstructures, resulting in an improvement in densification from 69.08% to 74.45% and a consequent reduction in porosity. The microhardness values also increased from 327.49 HV to 436.85 HV with an increase in Al content. However, corrosion behavior exhibited a non-monotonic trend. The alloy containing 1.4 at.% Al demonstrated the lowest corrosion current density (1.3522 × 10^–8 A/cm²) and the most noble corrosion potential, indicating improved passive film stability. At higher Al content (1.7 at.%), increased electrochemical activity was observed, likely due to microphase segregation and electrochemical heterogeneity. The results establish that controlled low-level aluminum addition enables optimization of the hardness–corrosion balance in SPS-processed TiCuNiSi_xAl high-entropy alloys, with 1.4 at.% Al providing the most favorable combination of densification, mechanical strengthening, and corrosion resistance.

Recommended Citation

Aramide, Basiru Philip; Jamiru, Tamba; Adegbola, Taoreed Adesola; Ayorinde, Thomas; Aramide, Fatai Olufemi; and Popoola, Abimbola Patricia Idowu (2026) "Effect of Al Content on Microstructure, Microhardness and Corrosion Resistance of Spark Plasma Sintered TiCuNiSi-Al High Entropy Alloy," Engineering and Technology Journal: Vol. 44: Iss. 6, Article 3.
DOI: https://doi.org/10.30684/2412-0758.1546

DOI

10.30684/2412-0758.1546

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