Structure and micro-hardness of titanium alloy Ti10Mo8Nb6Zr after high pressure torsion

• Main Authors: Gunderov, Dmitry, Churakova, Anna, Kiseleva, Svetlana, Gunderova, Sophia, Pedro, Joao, Claro, Ana Paula Rosifini Alves
• Format: Conference Proceeding
• Language: English
• Subjects: Beta phase; Boundaries; Dislocation density; Fine structure; Grains; High pressure; Medical materials; Microhardness; Surgical implants; Titanium alloys; Titanium base alloys
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0100267

The team of the Sao Paolo University (Brazil) developed a new β-Ti alloy Ti10Mo8Nb6Zr, which is perspective as material for medical implants. The structure and micro-hardness of titanium alloy Ti10Mo8Nb6Zr after high pressure torsion were studied. The XRD analysis showed that β-phase was the main phase of Ti10Mo8Nb6Zr alloy in the initial state. After high pressure torsion, β-phase remains the main one. There is also an additional α-phase, but its amount is low (below 10%). The half-width of a primary X-ray line of β-phase is greatly increased after HPT. This testifies to an increased density of dislocations and refinement of grains during HPT. According to TEM, after HPT a nanosized structure is formed. The TEM studies show that the alloy after HPT n=0.5 and n=5 contains both sub-grains with low-angle sub-boundaries and grains with high-angle boundaries and a high density of dislocations. Even after HPT with a relatively low n (n=0.5) a rather fine structure is formed with a size of grains/sub-grains of about 200-500 nm. After HPT with n = 5, the microstructure of Ti10Mo8Nb6Zr alloy is additionally refined, but the size of grains/sub-grains is about 200-300 nm. HPT with a low number of revolutions n=0.5 leads to a substantial growth of HV from 326 to 400. Further increase in the number of revolutions leads to additional growth of microhardness. The HV increment after HPT of this alloy (about 20%) is much lower than that after HPT of titanium and α-Ti alloys.