Laser-assisted ablation and plasma formation of titanium explored by LIBS, QCM, optical microscopy and SEM analyses along with mechanical modifications under different pressures of Ar and Ne

Abstract

The present study deals with the investigation of Nd: YAG laser assisted ablation and plasma formation of (Ti) at irradiance of 0.85 GW/cm2 under (Ar) and (Ne) environment at various pressures ranging from 10 to 120 Torr. Laser Induced Breakdown Spectroscopy (LIBS) is used to evaluate plasma parameters, whereas, Quartz Crystal Microbalance (QCM) is used for ablation yield measurements. The crater depth is evaluated by optical microscopy, surface features are explored by Scanning Electron Microscope (SEM) analysis and micro-hardness is measured by Vickers hardness tester. It is observed that plasma parameters are higher in Ar than in Ne, and are strongly correlated with ablation yield, ablation depth, surface features and hardness of laser ablated Ti. These parameters increase with increasing the pressure of environmental gasses, attain their maxima at 40 Torr for Ar and at 60 Torr for Ne. Afterwards they show a decreasing trend up till maximum pressure of 120 Torr. The maximum value of electron temperature (Te) is 5480 K, number density (ne) is 1.46×〖10〗^18 cm^(-3), ablation depth is 184 μm, ablation yield is 3.9×〖10〗^15 atoms/pulse and hardness is 300 HV in case of Ar atmosphere. SEM analysis reveals the growth of surface features like cones, ridges and pores whose appearance is more distinct in Ar than Ne and is attributed to temperature, pressure and density gradients along with recoil pressure of Ti plasma.