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This research explores how adding titanium affects the microstructure and mechanical properties of Co–Cr–Mo alloy.

February 7, 2026Scientific Reports0 citationsOpen Access

Effect of Ti addition on microstructure and mechanical properties of Co–Cr–Mo alloy developed by µ-plasma arc metal powder additive manufacturing process

BNBalbir Singh NegiIndian Institute of Technology Indore PAPradyumn Kumar Arya NJNeelesh Kumar JainIndian Institute of Management Indore

Key Points

This research explores how adding titanium affects the microstructure and mechanical properties of Co–Cr–Mo alloy.
Addition of 4 wt.% Ti to Co–Cr–Mo alloy using µ-plasma arc metal powder additive manufacturing process.
Assessment of microstructure, phase evolution, mechanical properties including flexural strength, yield strength, and microhardness.
Grain refinement in Co–Cr–Mo–4Ti alloy enhances tensile yield strength and % elongation.
Microhardness increased from 382 MPa to 473 MPa due to new phase formations.
Reduced porosity and density improve the durability and suitability for knee prostheses.

Abstract

This paper presents effects of addition of 4wt.% of Ti to Co-Cr-Mo alloy by µ-plasma arc metal powder additive manufacturing (µ-PAMPAM) process on microstructure, phase evolution, bending strength, tensile and compressive yield and ultimate strength, % elongation, microhardness, porosity, and density of the resultant alloy and their comparison with Co-Cr-Mo alloy. Microstructure and phase evolution study of Co-Cr-Mo alloy showed Co-rich matrix comprising of γ-Co and ε-Co phases, formation of Cr 7 C 3 and Cr 23 C 6 carbides due to presence of carbon and affinity of Cr towards it, and micro-cracks. Addition of 4 wt% Ti to Co-Cr-Mo alloy refined its grains, minimized formation of micro-cracks, led to formation of β-Ti phase and Co-Ti intermetallic compound along with the chromium carbides. It also reduced porosity and density of the resultant Co-Cr-Mo-4Ti alloy. Grain refinement increased flexural strength of Co-Cr-Mo-4Ti alloy. Solid solution effect of Ti increased tensile and compressive yield strength, ultimate compressive and tensile strength, and percentage elongation of Co-Cr-Mo-4Ti alloy as compared to Co-Cr-Mo alloy. Microhardness of Co-Cr-Mo-4Ti alloy increased to 473 MPa from 382 MPa of Co-Cr-Mo alloy due to formation of Co-Ti intermetallic compound and β-Ti phase. All these improvements enhance durability and strength of Co-Cr-Mo-4Ti alloy along with a reduction in stress shielding effect as compared to the Co-Cr-Mo, making it more suitable for knee prothesis applications.

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