Effects Of Additional Elements On The Glass Forming Ability And Mechanical Properties Of Bulk Zr-based Amorphous Alloys

The influence of glass forming ability (GFA), thermal stability and mechanical properties, as well as formation mechanism of amorphous alloys, is one of important issues for materials science. At present, this is also one of key research directions in amorphous materials and physics. Element addition technique plays an effective and important role in increasing the GFA of alloys, enhancing the thermal stability of amorphous phase, and improving mechanical properties of amorphous alloys. Moreover, element addition technique is an effective method to explore novel amorphous materials and improve their properties.In the present work, we used Zr₆₀Ni₂₂Al₁₈ alloys as base alloys and pertinently selected inexpensive element Fe and family element Ti as additions. Using the magnetic suspension melting technique and copper mold suction method, we investigated the influence of addition of Fe and Ti elements on the GFA, thermal stability and mechanical properties of Zr₆₀Ni₂₂Al₁₈ alloys, and further probed into the influence of element additions on the room temperature compression fracture of Zr-based amorphous alloys. In addition, we also studied the influence of addition of metalloid element P and B on the structural evolution and mechanical properties of rapidly solidified Zr₇₁Fe₁₅Cu₁₄ alloys using copper mold suction method. From the viewpoint of research direction, the present study supplies general experimental and theoretical bases for the fabrication of metallic amorphous materials/composites making the use of element additions and the improvement of their mechanical properties. Therefore, our work is very important for the exploration of new amorphous alloy systems and for the optimization of alloy compositions. We mainly used X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy(SEM), WDW-100J pressure testing machine in this work. The research contents and conclusions are described as follows.The alloying ingots with compositions of (Zr_0.60Ni_0.22Al_0.18)_100-xFe_x(x=0, 2, 4, 6, 8, 10) were prepared by the magnetic suspension melting the mixture of Zr, Ni, Al, and Fe metals. Sample rods with a diameter of 3mm were fabricated by casting the master ingots into copper mold. XRD patterns observations demonstrate that bulk metallic glass matrix composites containing crystalline precipitates will be obtained when the content of Fe element is 2%. The crystalline precipitates are Zr₃Fe, Ni₄₂Zr₅₈, and unknown phase. The other amount of Fe element does not change the monolithic amorphous structure of the obtained alloys. DSC thermal analysis of (Zr_0.60Ni_0.22Al_0.18)_100-xFe_x(x=0, 4, 6, 8, 10) show with the content of Fe element increasing, the supercooled liquid regionΔT_x first increase, then decrease, when the content of Fe element is 0-6%, (ΔT_x)_max=105K, (ΔT_x)_min=75K. When x=6～10,ΔT_x first decrease, then increase, (ΔT_x)_max=81K, (ΔT_x) min=44K. The glass transition temperature T_rg is in 0.5017-0.5684 range. The room temperature compression fracture experimental analysis shows that the Zr-based amorphous fracture strength was enhanced with the addition of Fe element in (Zr_0.60Ni_0.22Al_0.18)_100-xFe_x(x=0, 4, 6, 8, 10) alloys. The amorphous fracture strength can reach 2006MPa as the content of Fe element is 4%.The alloying ingots with compositions of (Zr_0.60Ni_0.22Al_0.18)_100-xTi_x(x=0, 2, 4, 6, 8) were prepared by the magnetic suspension melting the mixture of Zr, Ni, Al, and Ti metals. Sample rods with a diameter of 3mm were fabricated by casting the master ingots into copper mold. XRD patterns observations demonstrate that bulk metallic glass matrix composites containing crystalline precipitates will be obtained when the content of Ti element is 4%. The crystalline precipitates are NI₁₀Zr₇ and unknown phase. The other amount of Ti element does not change the monolithic amorphous structure of the obtained alloys. DSC thermal analysis of (Zr_0.60Ni_0.22Al_0.18)_100-xTi_x(x=0, 2, 4, 6, 8) show with the content of Ti element increasing, the supercooled liquid regionΔT_x first increase, then decrease, (ΔT_x)_max=105K, (ΔT_x)_min=38K. The glass transition temperature T_rg is in 0.4723-0.5113 range. The glass transition (Tg) was reduced as the increase of Ti content. T_rg is lowed to 0.4723 as the content of Ti element is 2%. The room temperature compression fracture experimental analysis shows that the Zr-based amorphous fracture strength first increases, then decrease, with the addition of Ti element in (Zr_0.60Ni_0.22Al_0.18)_100-xTi_x(x=0, 2, 6, 8) alloys. The amorphous fracture strength and plastic strain can reach 2006MPa and 3.94% respectively as the content of Ti element 6%.The alloying ingots with compositions of (Zr_0.71Fe_0.15Cu_0.14)_100-xM_x(M=P, B, x=0～5 at%) were prepared by the magnetic suspension melting the mixture of Zr, Fe, Cu, P or B metals and metalloid. Sample rods with a diameter of 3mm were fabricated by casting the master ingots into copper mold. XRD patterns observations demonstrate that the alloy structure is made from the amorphous phase, intermetallic and Zr element. The height of crystal diffraction peaks becomes smaller as P or B content increases. The room temperature compression fracture experimental analysis shows that the fracture strength become bigger as P or B content increases. The fracture strength can reach 618MPa as additional P element and can reach 1398MPa as additional P element.