Stiffness and hardness gradients obtained by laser surface melting of an aged β-Ti alloy

• Published in: Materials letters Vol. 260; p. 126901
• Main Authors: da Costa, Fernando Henrique, Pinhão, Rodrigo, dos Anjos, Sergio, Caram, Rubens, Fogagnolo, João Batista
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2020; Elsevier BV
• Subjects: Beta phase; Biomedical materials; Chemical precipitation; Cooling rate; Elastic modulus; Graded materials; Hardness; Heat affected zone; Laser cooling; Laser processing; Materials science; Melting; Orthopaedic implants; Orthopedics; Precipitates; Stiffness; Substrates; Surface layers; Surgical implants; Titanium alloys; Titanium base alloys; Laser processing; Titanium alloys; Elastic modulus; Graded materials
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2019.126901

[Display omitted] •A new route using LSM to obtain a property gradient in Ti alloy is proposed.•A surface layer with full β phase over an aged β-Ti alloy was obtained.•The β-phase solution in the surface layer reduced the elastic modulus and hardness.•LSM of an aged β-Ti alloy can produce a less rigid coating with lower hardness. Components with variable stiffness have been attracting interest because of their potential for use in biomedical implants. Here, a β-titanium alloy aged under different conditions was subjected to laser surface melting (LSM). The high cooling rate typical of LSM avoided α-phase precipitation in the fusion zone (FZ) and heat-affected zone (HAZ) as the α precipitates were solid-solutioned into the β phase, producing a surface layer with full β phase over the aged substrate and reduced stiffness and hardness. The decrease in stiffness occurred independently of the aging condition used while the decrease in hardness was greater for the sample aged at the lower temperature as this had finer precipitates. A route involving aging at this lower temperature and LSM is proposed for use when a graded material combining a less rigid surface with the original core stiffness and strength is required, as in orthopedic implants.