Structural, Microstructral, Mechanical and Magnetic Characterization of Ball Milled Tungsten Heavy Alloys

Abstract

A homemade ball mill was constructed and optimized in order to prepare nano crystallite size of tungsten heavy alloys, with composition of 90W-7Ni-3Fe and 90W-7Ni-3Co in wt%. The samples were mechanically alloyed under high purity of argon atmosphere and were sintered under high vacuumat 1200˚C, 1300˚C and 1400˚C. X-ray diffraction (XRD), Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX), Vickers, ultrasonic techniques and SQUID magnetometer were all used to characterize the studied samples. The sintering temperature and the milling time at which the heavy tungsten alloys were obtained, are discussed in details. The results showed that the tungsten heavy alloys were synthesized and sintered at lower temperature than those prepared by the conventional techniques. Moreover, the strains and relative densities increased with milling time up to 100 hrs; then decreased with further milling. On the other hand, the elastic moduli and hardness increased with milling time up to 200 hrs; then decreased with further milling. The hardness calculated from ultrasonic and measured from Vickers exhibited a similar trend though with different values. The saturated magnetization decreased by increasing the milling time and decreasing the crystallite size.

Effect of Milling Parameters on the Structural, Microstructural and Physical Properties of Alumina-Titania-Graphite Nanocomposite

“…The reduction of green density continues after 10 h of milling. Higher milling period (10 h) cause an increase of friction forces between powder particles [18] as a result of Van der Walls interaction and increase of intermolecular distance between the ceramic particles [19]. Meanwhile, graphite particles possibly act as a lubricant which facilitates movement and rearrangement of matrix/reinforcement particles causing higher densification.…”

High Densification of Tungsten via Hot Pressing at 1300 °C in Carbon Presence

“…There are several tungsten alloys which allow sintering temperature reduction from 2500 °C for pure tungsten [ 4 ] to as low as 1300 °C for 96% density of a W-Ni-Fe-Co mechanically alloyed system [ 5 ], 1200 °C for 98% density of a W-Ni-Cu-Mn system [ 6 ], and even 1100 °C for 96% density of a W-Cu-Sn-Fe system [ 6 ]. However, most reduced sintering temperature alloys contain more than 10 wt.% of low-melt additives introduced into the material matrix.…”