Vol.:(0123456789) 1 3 Metals and Materials International https://doi.org/10.1007/s12540-020-00861-z Nitrogen Ions Implantation in W‑Based Quad Alloy: Structure, Electrical Resistivity, Surface Roughness and Vickers Hardness as a Function of Ion Dose Muhammad Zakria Butt 1  · Dilawar Ali 2  · Muzamil Aftab 1  · Farooq Bashir 3  · M. Shahid Pervaiz 1  · M. Usman Tanveer 1  · M. Waqas Khaliq 1 Received: 8 June 2020 / Accepted: 17 August 2020 © The Korean Institute of Metals and Materials 2020 Abstract Five W-alloy specimens, containing 8.57% Ni, 6.34% Cu, and 1.34% Mo, were bombarded with 5.2 MeV singly charged nitrogen ions. The ions dose range was 5 × 10 14 –1 × 10 16  ions/cm 2 . XRD patterns portrayed diffraction peaks of pure W as well as of Cu 0.4 W 0.6 , MoNi 4 , and Ni 4 W phases. Harris analysis showed that the preferentially oriented planes depend on the nitrogen ions dose. The structural parameters, namely lattice strain and crystallite size, vary with nitrogen ions dose alike. Same pattern is followed by surface hardness and electrical resistivity. The increase in the values of all the parameters with ions dose is rapid in the range 0–1 × 10 15  ions/cm 2 and later on slow till the maximum ions dose 1 × 10 16  ions/cm 2 . How- ever, the interdependence of each parameter on the other ones was linear. Surface roughness of the specimens was found to decrease on increasing ions dose. On the other hand, surface hardness registers a rise as crystallite size increases, and hence follows Inverse Hall–Petch relation. Keywords W-alloy · N +1 ions implantation · Structural analysis · Electrical resistivity · Scanning electron microscopy · Surface hardness 1 Introduction It is well established that nitrogen implantation in metals, alloys, and composite materials can modify their surface properties [e.g. 1–8]. The main features of interest are sur- face hardness, resistance to wear, friction coefficient, fatigue resistance, crystallite size, corrosion performance, and for- mation of chemical compounds, etc. Yabe et al. [1] implanted thirteen 99.9% pure metals (Cu, Al, Ni, W, Fe, Nb, Ta, V, Co, Mo, Sn, Ti and Zr) with 150 keV nitrogen molecular ions using doses of 3 × 10 17 and 1 × 10 18  ions/cm 2 . The surface layers of the implanted metals were analyzed by means of RBS and XRD techniques. For the smaller 3 × 10 17  ions/cm 2 dose, the implanted layer of target metals was nitrided only to some extent. In Ta, V, Ti and Zr target metals, solid solution formation occurred together with an isotropic expansion of the lattice of V and Ta (cubic metals) and an anisotropic c-direction expansion in Ti and Zr lattice (hexagonal metals). When the implanted region was saturated with nitrogen, the nitride formed was quite stable. The quantity of nitrogen retained in the target metal increased whereas the heat of formation of the nitride decreased. The amount of nitrogen retained was a function of the reactivity of target metal to nitrogen. Zhang et al. [2] investigated the influence of 40 keV N + ions implantation on the surface of W specimens. The implantation doses used were 4 × 10 17 , 8 × 10 17 , and 1.6 × 10 18  ions/cm 2 . Characterization of the specimens was done by XRD and XPS techniques. WN and W x (O, N) phases was formed in the target near-surface layer due to N + ions implantation. The concentration of WN phase increased with the increase in N + ions dose which was accompanied by concomitant decrease in concentration of W x (O, N). * Muhammad Zakria Butt mzakriabutt@gmail.com 1 Centre for Advanced Studies in Physics, GC University, Lahore 54000, Pakistan 2 Department of Physics, GC University, Lahore 54000, Pakistan 3 Central Research Laboratories, LCW University, Lahore 54000, Pakistan