Significant Super-cooling Technology For Fe-based Bulk Metallic Glasses And Their Glass-forming Ability

In this paper, by increasing the ability of deeply undercooling through composition design, a series of amorphous samples of Fe-based and Co-based alloys are prepared using industry raw material. The tests of metallographic observation and X-ray diffraction have carried out for these samples to ascertain their microstructure and glass-forming ability. The thermodynamics characteristic and mechanical properties of amorphous samples has been obtained by means of differential scanning analysis and compressive test. Thus, some Fe-based and Co-based amorphous alloys with good glass-forming ability and outstanding mechanical properties have been prepared.The result shows that, the partial replacement of Fe with a certain amount Ni in Fe₄₈Cr₁₅Mo₁₄C₁₅B₆Y₂ alloy will increases its glass-forming ability and compressive fracture strength significantly. Among them, the Fe₄₈Ni₂Cr₁₅Mo₁₄C₁₅B₆Y₂ alloy has the best glass-forming ability and the critical size for glass formation has reached 7 mm; the Fe₄₇Ni₁Cr₁₅Mo₁₄C₁₅B₆Y₂ alloy has the best compressive fracture strength of 2997.9 MPa.A serious of Fe-B-Y alloys was designed according to the ternary phase diagram. The results by the analysis of rapid quenching structure of Fe₈₁B₉Y₁₀ show that some special microstructure was obtained.A replacement of Fe with Co in Fe₄₈Cr₁₅Mo₁₄C₁₅B₆X₂(X=Gd, Y, Er) alloys has lead to incensement of glass-forming ability, and the rod samples diameter with the best glass-forming ability up to 7 mm has been obtained when the X is Er. Moreover, the effect of each rare earth element on glass-forming ability of alloys is different obviously.Few addition of Nb to Fe-(Ni)-Cr-Mo-C-B-Y will improve glass-forming ability and mechanical properties. The Fe₍486Cr₁₅Mo₁₄C₁₅B₆Y₂Nb₂ alloy, whose amorphous rod samples diameter has reached 7 mm, shows best glass-forming ability; the Fe₄₇Cr₁₅Mo₁₄C₁₅B₆Y₂Nb₁ alloy has the best compressive fracture strength of 3645.7 MPa.. However, the combination both of Ni and Nb doesn't improve the glass-forming ability of Fe-Cr-Mo-C-B-Y alloys effectively.Experimental results show that the effect of Ni or Nb on glass-forming ability and mechanical properties of Fe-Cr-Mo-C-B-Y alloys is obvious only when the addition is limited in a small content.