Study On Forming And Alloying Of Mg-Cu-Tb Bulk Amorphous Alloy

Mg-based alloys have great potential as engineering materials for automobile, aircraft and computer industries due to their high specific strength and abundance. In the papers, the Mg₆₅Cu₂₅Tb₁₀ bulk with high oxygen resistances was firstly prepared by the copper mold casting technique. The Mg₆₅Cu_25-xTb_10-yNi_xRE_y bulk amorphous alloys were prepared by the copper mold casting technique. And the effect of Ni addition and the rare earth (RE) addition on the glass forming ability (GFA) and mechanical properties were studied according to X-ray diffractrometry (XRD), differential scanning calorimeter (DSC) , compression tests and scaning electron microscopy (SEM). The main conclusions as follows:The Mg₆₅Cu₂₅Tb₁₀ bulk amorphous alloy rods with 3 mm diameters were prepared by the copper mold casting technique. From the endothermal signal of the melting, one can deduce that the composition of the alloy is very close to the eutectic point with highly glass froming ability and thermal stability. The compressive fracture strength and Young's modulus at room temperature are 756MPa and 54GPa, respectively.The effect of Ni addition and on the glass forming ability (GFA) and mechanical properties of Mg-Cu-Tb alloys were studied. With the increase of substitution of Ni for, the glass forming ability and thermal stability of the Mg₆₅Cu_25-xNi_xTb₁₀(x=0, 5, 10) alloys decreased. The Cu substitution by Ni (10%) will result in the detrimental impact on the GFA and decreasing the mechanical property. But after substitution of Ni for Cu from (5%) , the compressive fracture strength, increase clearly from 756 MPa to 867 MPa.The effect of rare earth (RE) addition on Mg based metallic glass was studied. After substitution of rare-earth element (Ce(3%)) and their admixtures (Ce(3%)+Y(3 %)) for Tb, the reduced glass transition temperature (T_rg) of the Mg₆₅Cu₂₀Ni₅Tb₇Ce₃ and Mg₆₅Cu₂₀Ni₅Tb₄Ce₃Y₃ alloys were increased orderly, and the supercooled liquid region, ΔT_x, increased. The new multielement Mg based metallic glasses with highly GFA and thermal stability are successfully fabricated owing to multielement -compounded principles and high oxidation resistance of rare-earth admixtures. But, these samples were very frail and their compressive fracture strengths were below 300 MPa, considerably less than that of Mg₆₅Cu₂₀Ni₅Tb₁₀.