en Research Paper Research Paper <span style="font-size:12pt"><span style="line-height:150%"><span new="" roman="" style="font-family:" times="">Investigation the structural and magnetic properties of nanocrystalline<b> </b>Co₇₈Zr₁₇B₂Si₁W₂ alloy during melt spinning and annealing processes were the main goal of this study. In this regard, samples were prepared using vacuum induction melting, melt spinning and subsequent annealing. The specimens were evaluated using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). Based on results, nanocrystalline Co₅Zr single phase with hard magnetic properties (Ms=29.5 emu/g and Hc=2.7 kOe) successfully formed during melt spinning process (at wheel speed of 40 m.s^-1). The coercivity value of rapid solidified sample increased to about 3.2 kOe during annealing process up to 400&deg;C. However, more increasing in annealing temperature lead to the transformation of non-equilibrium magnetic Co₅Zr phase to stable Zr₂Co₁₁phase, which has distractive effects on final magnetic properties.</span></span></span><br> &nbsp; Co-Zr alloy,Nanocrystalline,Melt-spinning,Magnetic properties 1 6 http://ijmse.iust.ac.ir/browse.php?a_code=A-10-1216-5&slc_lang=en&sid=1 Mohammad Molaahmadi molaahmadi@gmail.com 1800319475328460017366 1800319475328460017366 No Malek- Ashtar University of Technology Majid Tavoosi ma.tavoosi@gmail.com 1800319475328460017367 1800319475328460017367 Yes Malek-Ashtar University of Technology Ali Ghasemi ali13912007@gmail.com 1800319475328460017368 1800319475328460017368 No Malek- Ashtar University of Technology Gholam Reza Gordani gordoni@gmail.com 1800319475328460017369 1800319475328460017369 No Malek- Ashtar University of Technology