| The W-Ni-Fe alloys are the two-phase mixture material consisting of wolfram crystal phase and nickel and iron matrix phase, with many excellent features such as high density, high strength, corrosion resistance, anti-high temperature oxidation, strong ability of anti-γ ray, non-toxic and environmentally friendly, which are widely used in shielding equipment material of radiation environment.This dissertation adopts the method of liquid-phase-sintered, W-Ni-Fe alloys and W-Ni-Fe-Hf alloys sample are made by ball milling mixing-molded-vacuum sintering process. Under different experimental parameters using material testing machine tested mechanical capability such as sintered sample density, anti-tensile strength, elongation, microscopic hardness, using optical microscopy and scanning electron microscopy to observe alloy micro structure and fracture morphology. Besides, EDS and XRD are used to analyze micro-area composition and phase composition. We focus on studying the impact of sintering process and alloy composition to the microstructure, mechanical capability and γ radiation shielding capability of W-Ni-Fe alloys. The results are as follows:First: The alloy density, anti-tensile strength, elongation and micro hardness of W-Ni-Fe increase and then decrease along with the extension of sintering time. The density, elongation and micro hardness reach a peak at 45 min, the value of which are 16.99 gram per cubic centimeter, 10.1 percent and 439.91 HV, while the highest tensile strength is 852.81 Mpa at the time of 30min;Second: The alloy density, anti-tensile strength, elongation and micro hardness of W-Ni-Fe increase and then decrease along with the increasing of heating speed. While the maximum density is 17.0 gram per cubic centimeter, which appears when the heating rate is 20 degrees per minute, and the anti-tensile strength, elongation, micro hardness reach a peak at a heating rate of 30 degrees per minute, the value of which are 846.66 Mpa, 10.5percent and 439.91 HV;Third: The alloy density, anti-tensile strength, elongation and micro hardness of W-Ni-Fe increase and then decrease along with the increasing of nickel and iron ratio. When the nickel and iron ratio are in the range of 1 to 4, the dynamics performance of the samples is excellent. When the Ni/Fe ratio of alloy samples is 7:3, the dynamics performance is the best, the density of which can reach 16.99 gram per cubic centimeter, the tensile strength of which is 846.66 MPa, the elongation of which is 10.5 percent, the micro hardness of which is 439.91 HV. But when the Ni / Fe ratio is greater than 6, the mechanical properties will drastically decrease;The fourth:Comparing the Shielding performance of W-Ni-Fe alloys and lead weights consisting of different ratio of Ni/Fe with each other, we find that the difference of shielding performance is small. What’s more, the shielding ability of W-Ni-Fe alloys to γ-ray is stronger than lead weights. Besides, the shielding ability of 90W-7Ni-3Fe alloys is the best and the Half-absorption thickness of 90W-7Ni-3Fe alloys toγ-ray is 63.8 percent of lead weights’ thickness;The fifth: Adding alloying elements Hf of W-Ni-Fe alloy has the effect of solid solution strengthening, W-Ni-Fe alloy’s mechanical properties with the increase of the content of Hf first increases and then decreases trend, when adding 0.9% Hf W-Ni-Fe alloy has very excellent mechanical properties, the sintering state density is 17.07 g/cm3, the tensile strength of 925.33 MPa, elongation is 8.1% and 560.82 HV hardness;The sixth: The result shows that the absorption coefficient of W-Ni-Fe-Hf alloys to γ-ray increases as the content of Hf increases. However, the semi-absorption thickness decreases as the content of Hf increases. And the shielding perform to γ-ray is best when 1.5 Hf W-Ni-Fe alloys are added.Mean-while, the absorption coefficient of γ-ray is 0.18424 and the semi-absorption thickness is 3.76 mm... |
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