Preparation And Properties Of New-type Soft Magnetic Fe-based Bulk Metallic Glasses

Fe-based bulk metallic glasses?BMGs?have promising application prospects in the field of high-performance magnetic functional materials due to their excellent soft magnetic properties.Most of BMGs,however,contain glass-forming metal elements such as Al,Ga,Nb,Mo,Y and so forth.Those glass-forming metal elements in Fe-based BMGs although effectively improved the glass forming ability?GFA?of alloys,also decreased the saturation magnetization and increased the material cost.Therefore,it is perfective meaningful to develop a new“Fe-metalloids”type BMGs without any glass-forming metal elements mentioned above and with high GFA and good soft magnetic properties,simultaneously.The development of high-entropy bulk metallic glasses?HE-BMGs?provided a novel and effective idea for the component design of bulk glassy alloys.Rencently,we have successfully developed Fe-Co-Ni-?P,C,B?and Fe-Co-Ni-?B,Si?HE-BMGs with good soft magnetic properties and superior strength.However,the GFA both of two HE-BMGs are relatively weak.Hence,it is always an worthy research topic to develop a new soft magnetic HE-BMGs with higher GFA than that of Fe-Co-Ni-?P,C,B?and Fe-Co-Ni-?B,Si?HE-BMGs.This work,from the base Fe₇₅P₁₀C₁₀B₅ metallic glass,developed new soft magnetic Fe-P-C-B-Si BMGs and Fe-Co-Ni-?P,C,B,Si?HE-BMGs with high GFA by the similar-elements replacement method,respectively.The relations between the alloy compositions and thermal properties,GFA,soft magnetic and mechanical properties of the Fe-P-C-B-Si BMGs and Fe-Co-Ni-?P,C,B,Si?HE-BMGs have been investigated and the mechanisms of high GFA were clarified.The principal conclusions are shown as follows:1.The addition of Si element improves the GFA of Fe-P-C-B alloys.The critical diameters?d_c?of Fe₇₅P₁₀C₄B₅Si₆ and Fe₇₅P₁₀C₂B₅Si₈ samples both are 4 mm which is the maximum size in the“Fe-metalloids”type BMGs at present.2.The Fe-P-C-B-Si BMGs exhibit excellent soft magnetic and mechanical properties.Their saturation magnetization?B_s?,coercivity?H_c?,compressive yield strength??_y?and plastic strain??_p?are in the range of 1.37-1.40 T,0.62-2.80 A/m,3145-3668 MPa,2.7-6.1%,respectively.3.The new Fe-based BMGs with the highest B_s of 1.64 T were developed by increasing the Fe content and adjusting alloy components based on the Fe-P-C-B-Si BMG.4.A new high entropy bulk metallic glasses?HE-BMGs?were fabricated in the TM?P,C,B,Si?₂₅(TM=Fe₂₅Co₂₅Ni₂₅)alloy system.The BMGs rods were obtained in a wide composition range of TM(P_0.3–0.5C_0.1–0.3B_0.2–0.3Si_0.1–0.3)₂₅,in which the TM(P_0.4C_0.2B_0.2Si_0.2)₂₅and TM(P_0.5C_0.1B_0.2Si_0.2)₂₅ alloys possess the largest critical diameter of 2.0 mm.5.The TM?P,C,B,Si?₂₅ HE-BMGs exhibit good soft magnetic and mechanical properties.The B_s,H_c,?_y and?_p of TM(P_0.4C_0.2B_0.2Si_0.2)₂₅5 alloy are 0.85 T,0.8 A/m,3076MPa and 1.9%,respectively.6.The mechanisms of high GFA of TM?P,C,B,Si?₂₅ alloys were clarified by investigating the competing crystalline phases of TM(P_0.4C_0.2B_0.2Si_0.2)₂₅ HEA and Fe₇₅P₁₀C₁₀B₅ base alloy during the cooling process.The good GFA of the TM?P,C,B,Si?₂₅HEAs may be attributed to the simultaneous precipitation of the complicated?Fe,Co,Ni?₂₃?C,B?₆,?Fe,Co,Ni?₃B and?Fe,Co,Ni?₃P competing crystalline phases during the cooling process,which make the crystalline process become more difficult.