| Metal Silicides which has high melting point, high strength, the appropriate density and good oxidation resistance and corrosion resistance, is a great potential materials for high temperature structural,but its brittle is the key problem for the industrial application.It can effectively improve the metal silicide microstructure and properties by alloying. Based on theory,high-temperature M5Si3-type metal silicide was synthesized from element Mo, Nb and Si powders by mechanical milling activation and hot-pressing sintering technology.we make the research of the phase composition, microstructure, mechanical property and the property of corrosion of Mo-Nb-Si system silicides materials by XRD, OM, SEM and EDS etc.The (Mo1-x,Nbx)5Si3(x=0,0.4,0.6,1) alloys were prepared by MA/HP method. The EDS results show that the main phases of these alloys are Mo5Si3,α-Nb5Si3,γ-Nb5Si3 and the solid solution phase of (Mo,Nb)5Si3 andβ-(Nb,Mo)5Si3 solid solution.β-Nb5Si3 is stabilized by the Mo addition. With the content of Nb increasing, the room temperature hardness of the alloys increased, the indentation fracture toughness and compressive strength changes at first increasing then decreasing,for example, when x=0.6,the maximum indentation fracture toughness and compressive strength is 4.71MPa·m1/2 and 1637MPa.Research on corrosion about alloy samples (Mo1-x,Nbx)5Si3 (x=0,0.1,0.2,0.3,0.4) and the reference sample 304 stainless steel in 1mol/L H2SO4, 1mol/L HCl, 1mol/L NaOH solution. As we can see, from the polarization curves, there is passive zone in the alloy samples in 1mol/L H2SO4, 1mol/L HCl, 1mol/L NaOH solution; in 1mol/L H2SO4 and 1mol/L HCl solution.the alloy's corrosion potential is higher than 304 stainless steel while the corrosion current is far below the 304 stainless steel, that the corrosion current of 304 stainless steel is 50 times from the sample. However, in 1mol/L NaOH solution, the corrosion voltage of alloy specimens is lower than 304 stainless steel, the corrosion current has no difference, which indicated that the electro-chemical corrosion, the alloy sample resistance in H2SO4, HCl and NaOH solution is better than 304 Stainless steel. The corrosion resistance ability is much higher than 304 stainless steel, but corrosion resistance ability in NaOH solution is similar with 304 stainless steel.The alloy samples and the reference sample immersion in 1mol/L H2SO4,1mol/L HCl, 1mol/L NaOH solution after 100h, draw corrosion kinetics curves about the alloy sample and reference sample and the appearance is investigated through the scanning electronic microscope. From the curves, the alloy sample loses 1mg/cm2 while the lost weight of the304 stainless steel is up to 131.1mg/cm2 with longer time in H2SO4 and HCl solution. However, the corrosion weight loss of the alloys and of 304 stainless steel in NaOH solution are about 0.25 mg/cm2, indicating that the corrosion resistance ability of alloy samples is much higher than 304 stainless steel in H2SO4 and HCl,but in NaOH solution ,corrosion resistance ability of alloy samples has no difference 304 stainless steel.There is no appearance difference before and after corrosion on alloy sample, and there is also no corrosion pits and pitting except a small amount of grain boundary corrosion and corrosion spalling. There are some SiO2 oxide film, Mo and Nb accumulation layer shielding on the alloy surface. With the increase of Nb content in the alloy sample, the surface corrosion layer's density increases, so the corrosion resistance is better.
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