Fabrication and Characterization of novel W80Ni10Nb10alloy produced by mechanical alloying

R. Saxena, A. Patra, S. K. Karak, A. Pattanaik, S. C. Mishra
2016 IOP Conference Series: Materials Science and Engineering  
Nanostructured tungsten (W) based alloy with nominal composition of W 80 Ni 10 Nb 10 (in wt. %) was synthesized by mechanical alloying of elemental powders of tungsten (W), nickel (Ni), niobium (Nb) in a high energy planetary ball-mill for 20 h using chrome steel as grinding media and toluene as process control agent followed by compaction at 500 MPa pressure for 5 mins and sintering at 1500°C for 2 h in Ar atmosphere. The phase evolution and the microstructure of the milled powder and
more » ... powder and consolidated product were investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The crystallite size of W in W 80 Ni 10 Nb 10 powder was reduced from 100 µm at 0 h to 45.6 nm at 10 h and 34.1 nm at 20 h of milling whereas lattice strain increases to 0.35% at 20 h of milling. The dislocation density shows sharp increase up to 5 h of milling and the rate of increase drops beyond 5 to 20 h of milling. The lattice parameter of tungsten in W 80 Ni 10 Nb 10 expanded upto 0.04% at 10 h of milling and contracted upto 0.02% at 20 h of milling. The SEM micrograph revealed the presence of spherical and elongated particles in W 80 Ni 10 Nb 10 powders at 20 h of milling. The particle size decreases from 100 µm to 2 µm with an increase in the milling time from 0 to 20 hours. The crystallite size of W in milled W 80 Ni 10 Nb 10 alloy as evident from bright field TEM image was in well agreement with the measured crystallite size from XRD. Structure of W in 20 h milled W 80 Ni 10 Nb 10 alloy was identified by indexing of selected area diffraction (SAD) pattern. Formation of NbNi intermetallic was evident from XRD pattern and SEM micrograph of sintered alloy. Maximum sinterability of 90.8% was achieved in 20 h milled sintered alloy. Hardness and wear study was also conducted to investigate the mechanical behaviour of the sintered product. Hardness of W 80 Ni 10 Nb 10 alloy reduces with increasing load whereas wear rate increases with increasing load. The evaluated hardness value in the present study for all loads is lower than the literature reported hardness of nanostructured W.
doi:10.1088/1757-899x/115/1/012026 fatcat:233odpvkvrbgdltrjuvdgxt7gu