Alterations in the microhardness of a titanium alloy affected to a series of nanosecond laser pulses

Abstract

The alterations in the microhardness of a titanium alloy Ti85.85Al6.5Zr4Sn2Nb1Mo0.5Si0.15 subjected to laser treatment were investigated. Laser processing consists of a series of pulses with durations 20 ns. We used various methods of laser processing, which differed in power density, wavelength, geometrical pattern of irradiation and so on. The dependences of the microhardness on the load on the indenter were found. The laser processing modes providing the increased microhardness are determined. The investigations were carried out at loads from 0.49 N to 4.9 N, with maximum indentation depth of the Vickers pyramid up to 12 μm. Vickers microhardness can be increased by 20 – 40 %. At the same time, the plastic properties of the hardened layer are improved. The probability of crack formation during indentation of the initial alloy increased with a load on the indenter and reached 0.52 for a load of 4.9 N. In two of the treated areas of the three presented, crack formation was not recorded at any load. The mechanisms of hardening of the material surface layer under the influence of a laser pulse are discussed. Using the methods of computational mathematics, the character of sample heating under the influence of a single laser pulse is determined. The perspectives for the development of the proposed processing method are permitting to obtain the optimal mechanical properties of the hardened layer are discussed.

Targeted Alternation in Properties of Solid Amorphous-Nanocrystalline Material in Exposing to Nanosecond Laser Radiation

“…2, are typical for the one-sided material treatment. However, there is a possibility of simultaneous improvement of mechanical characteristics during for the two-sided treatment of samples [26,28]. Such treatment can significantly increase the required parameters while preserving the unique physical properties of an amorphous-nanocrystalline metal alloy.…”

Influence of Laser Modification on the Surface Character of Biomaterials: Titanium and Its Alloys—A Review

“…The study on the hardness of a titanium alloy was carried out by Khorram et al [124] which indicated an increase in hardness of 36%. Additionally, Zhang et al [125] indicated an increase in hardness after laser modification of 60%, while Ushakov et al [126] determined that the possibility of increasing the Vickers hardness after a laser treatment ranged between 20% and 40%. Moreover, the increase in microhardness was accompanied by an increase in the fracture toughness.…”

Mechanical Properties of Laser Treated Thin Sample of an Amorphous-Nanocrystalline Metallic Alloy Depending on the Initial Annealing Temperature

“…The local impact of the laser pulse is limited to the focus spot. The border region is mainly subject to condensation of the ionized phase from the gas-plasma torch and shock pressure [2,25,29].…”