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Mo 5 Si 3 in the Mo-Si system has the highest melting point, the most wide composition range, good oxidation resistance and creep resistance research in recent years become hot spots. But its room temperature brittleness severely hindered its widespread application. Currently, alloying and composite technology to improve Mo 5 Si 3 room temperature brittleness of commonly used methods. Meanwhile, Mo 5 Si 3 because of its high covalent chemical composition and good stability can be expected to have good corrosion resistance. This study is based on in-situ composite of thinking, MoO3 powder, Mo powder, Si powder and Al powder as raw material, the use of mechanical prepared by chemical reduction with nanocrystalline structure Al 2 O 3 / Mo 5 Si 3 composite powders and sintered prepared by combining Mo 5 Si 3 and 20% Al 2 O 3 / Mo 5 Si 3 composite materials. Using X-ray diffraction, laser particle size analyzer, scanning electron microscopy, optical microscope and energy dispersive spectroscopy and other composite materials in the preparation process for the structural evolution of microstructure and micro-area composition analysis and characterization, and composite mechanical properties and corrosion resistance study results showed that: raw material powder milled for 10h after a chemical reaction occurring machinery 20% Al 2 O 3 / Mo 5 Si 3 composite powders, faster response to the explosion of a similar self-propagating modes. With the milling time, the grain size decreases composite powders, micro strain increases, the relationship between the two was inverter. After milling 100h, Al 2 O 3 and Mo 5 Si 3 grain sizes were 38.3nm and 39.8nm, with a nanocrystalline structure. Powder refinement occurs mainly in the early milling, ball milling after 100h curve submicron particle size and micron bimodal distribution, particle size is small, at between 1 ~ 3μm. Sintered prepared 20% Al 2 O 3 / Mo 5 Si 3 composite main phases Al 2 O 3 , Mo 5 Si 3 and a very small amount of Mo3Si. Al 2 O 3 and the matrix material Mo 5 Si 3 no chemical reaction between the composite component between the good thermal stability. Al 2 O 3 to join the fine matrix material organization, pinning the grain boundaries and dislocations, toughening the matrix; 20% Al 2 O 3 / Mo 5 Si 3 composite material has good mechanical properties. Its hardness, compressive strength, flexural strength and fracture toughness were 1409HV, 1419MPa, 346MPa and 5.48 MPa · m 1/2 , more pure Mo 5 Si 3 sample has been greatly improved. With the tough phase Al 2 O 3 to join the composite fracture mode into the transgranular fracture along the grain - a mixed transgranular fracture. Mo 5 Si 3 and 20% Al 2 O 3 / Mo 5 Si 3 composite material has good resistance to H 2 SO 4 and HCl solution corrosion, the corrosion resistance is much better than traditional corrosion resistant materials 304 stainless steel. In H 2 SO 4 and HCl solution soak after 100h, the reference sample of 304 stainless steel corrosion weight loss is as high as 131.1mg/cm 2 for Mo 5 Si 3 and 20% Al 2 O 3 / Mo 5 Si 3 composite corrosion weight loss of more than 100 times. In NaOH solution, Mo 5 Si 3 SiO2 passivation film surface of NaOH in solution reacts with Na 2 SiO 3 , undermine the integrity of the passive film, corrosion resistance is poor. Join toughness Al 2 O 3 after, 20% Al 2 O 3 / Mo 5 < / sub> Si 3 composites significantly improved corrosion resistance, corrosion resistance of 304 stainless steel. Test material has good corrosion resistance, the corrosion mechanism is: composite component elements Mo, Si passivation and so has a strong ability in material surface MoO 2 , SiO 2 < / sub> and Al 2 O 3 passivation film to prevent corrosion of the substrate. In addition, the test material has a high chemical stability, can effectively resist the erosion ion etching solution, with a good corrosion resistance.
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