Effect Of Fe-B-Si-Nb-Cr Amorphous Inoculation On The Microstructure And Properties Of ZL401 Alloy

Although ZL401 alloy has good casting performance,excellent room temperature mechanical properties,cutting performance and welding performance,its poor corrosion resistance and high temperature toughness limit its application fields.In this paper,Fe_(72-X)B₂₀Si₄Nb₄Cr _X(X=0,1,2,3)amorphous alloy is used as the inoculant to study the effects of the addition amount of amorphous alloy and inoculant treatment process on the microstructure and properties of ZL401 alloy.The ZL401 alloy after inoculation which structure refinement mechanism,high temperature strengthening mechanism and electrochemical corrosion behavior has analyzed.The main research results are as follows:(1)DSC experiments show:Fe_(72-X)B₂₀Si₄Nb₄Cr _X(X=0,1,2,3)amorphous alloy which temperatures T_gare 820K,788K,766K and 830K for the four amorphous alloys measure at a heating rate of 30K/min.The crystallization temperatures T_xare 882K,852K,833K and879K.The melting temperatures T_m are 1402K,1409K,1436K and 1413K and the supercooled liquid phase areas?T_x are 62K,64K,67K,49K,respectively.(2)The refinement effect of the prepared inoculated alloy is remarkable.The size of the matrix phase is small and distributed uniformly.The eutectic Si organization which distribute in the matrix uniformly changed from large coarse dendrites to small dendrites.The size of?-Al dendrites of the uninoculated alloy is about 100-150?m and the best refinement effect was ZL401 alloy after Fe₇₀B₂₀Si₄Nb₄Cr₂ amorphous inoculation.The smallest dendrite size of 36?m was obtained with the addition of 0.2wt.%Fe₇₀B₂₀Si₄Nb₄Cr₂ amorphous and the eutectic Si size is smaller which more uniformly distributed.The best room temperature mechanical properties are obtained for Fe₇₀B₂₀Si₄Nb₄Cr₂ amorphous nurture alloy.When0.2wt.%Fe₇₀B₂₀Si₄Nb₄Cr₂ amorphous is added and the inoculation time is 30 min,the tensile strength of modified ZL401 alloy is 300.6 MPa.(3)The inoculation mechanism of ZL401 alloy that after amorphous is added to the aluminum alloy melt,it will instantly crystallize and form fine nano-phase Fe₂B phase,Fe-Cr phase and Fe₃Si phase,the crystallization temperatures T_xare 882K,852K,833K and879K,which Fe₂B phase as the heterogeneous nucleation core of?-Al phase.(4)It is shown that the tensile strength of the inoculation alloy improves with the increase of the tensile rate at the same temperature.At the same tensile rate,the tensile strength of inoculation alloy decreases with the increase of temperature.When the tensile rate is 10^-3S^-1 at 433K,the optimal tensile strength of ZL401 alloy inoculated with0.2wt.%Fe₇₀B₂₀Si₄Nb₄Cr₂ amorphous is 293.2MPa.Compared with the uninoculated ZL401alloy,the tensile strength is increased by 72%.(5)Electrochemical corrosion experiments show that the corrosion rate increases as the p H value continues to decrease,ZL401 alloy exhibits better corrosion resistance after Fe₆₉B₂₀Si₄Nb₄Cr₁ amorphous incubation in an acidic environment;under alkaline conditions,as the p H value continues to increase,ZL401 alloy showed good corrosion resistance after Fe₇₀B₂₀Si₄Nb₄Cr₂ amorphous inoculation.