| By means of Liquid Phase Sintering (LPS), mechanical quality and micro-structure of tungsten high density alloys W-Ni-Fe and those alloys added with alloying element tantalum of different contents are investigated. The results show that under the condition of density 99.88% specimen fabricated by vacuum sintering 1480 ℃ X lh, elastic modulus of 90W-7Ni-3Fe is 286GPa through Three-Points Bending Method, strength 853Mpa, elongation 9% and hardness HRC 25.3. Elastic modulus decreases sharply with the increase of porosity. After 1100℃ and 1200℃ heating treatment, strength increases slowly and elongation, hardness are enhanced evidently, but elastic modulus has no apparent change. Sample microstructure is uniform and grain size is about 30 u m and four kinds of rupture exist in dominance of tungsten cleavage.In the range of 1-7% tantalum addition, alloys have no tremendous change in microstructure, thus elastic modulus approximately decreases as more alloying element is added. Critical point exists in the plot of strength-Ta content, namely 5%Ta, the tensile strength is as high as 1164 MPa, theretofore it increases as more Ta content is doped, but decreases subsequently. Ta blocks alloys densification, and density is in the range of 96-98.5% when sintered at 1440℃. Plasticity deteriorates and all the values are lower than 6% except specimen with 7%Ta adding. Elastic modulus of 85W-5Ta-7Ni-3Fe alloy changes scarcely after 1100℃ and 1200℃ heating treatment, but strength increases appreciably. Elongation almost has no change when treated at 1100℃, yet decreases to 4% at: 1200℃. All adulterated alloys are much harder than original W-Ni-Fe alloy, that of 85W-5Ta-7Ni-3Fe is up to HRC35.0. The solution degree of tungsten in y phase decreases because of Ta solution in matrix, therefore the kinetic rate constant is depressed, W grain size is attenuated and the degree is more obvious with the increase of Ta addition. Alloy's fracture mode changes with the prominence of tungsten cleavage and matrix intergranular rupture.Compressibility of powders is improved when more Ta is added (>10%), namely green's spring back is declined and pressed density increased. Because in alloys with Ta a new phase Ta appears and its content is comparative with W and matrix phase elastic modulus differs from that of alloys with lower Ta adoption. Elastic modulus increases markedly when more Ta is added, i.e. elevating 286 GPa possessed by alloy with 40% Ta from 210 GPa of 10% Ta added alloy. Meanwhile thestrength is reduced completely by reason of the abundance of Ta in alloy . All specimens bear a certain degiee of pores, thus they have an elongation capability lower than 3%, and yet hardness is elevated when alloys have a larger Ta content. Tungsten grain appears finer as 10% and 20% Ta are doped to alloys, while Ta addition is up to 30%, Ta and W grain configuration change greatly and are not spherical in shape. Matrix intergranular rupture and tungsten cleavage are still important manners in the micrograph of 80W-10Ta-7Ni-3Fe alloy, and lots of fine W grain separates with matrix, which determines its bad tensile strength. Particle size possesses influence on densification, strength, elongation, elastic modulus and micrograph of 80W-10Ta-7Ni-3Fe alloy.
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