A Series of Zr-Based Bulk Metallic Glasses with Room Temperature Plasticity

Abstract

A group of plastic Zr-Al-Ni-Cu bulk metallic glasses (BMGs) with low Zr content was developed and their thermal and mechanical properties were investigated. The results show that these Zr-based BMGs have a single crystallization event for all heating rates in the studied temperature region. The glass transition temperature Tg decreases with increasing Zr content for all heating rates. There are two melting procedures for the BMGs whose Zr content is less than 52 at %, while three melting procedures for the other Zr-based BMGs. The second melting procedure is split into two melting procedures for Zr52.5Al12.2Ni12.6Cu22.7 and Zr53Al11.6Ni11.7Cu23.7 BMGs, while the first melting procedure is split into two melting procedures for the other BMGs. The activation energy decreases with increasing sensitivity index β for the studied Zr-based BMGs. The plastic strain εp is in the region of 0.2%–19.1% for these Zr-based BMGs. Both yield strength σy and fracture strength σf are smallest for Zr55Al8.9Ni7.3Cu28.8 BMG whose εp is largest among all studied Zr-based BMGs and reaches up to 19.1%. In addition, the mechanism for the large difference of the plasticity among the studied Zr-based BMGs is also discussed.

Activation volume and energy of bulk metallic glasses determined by nanoindentation

“…The activation energy shows also an increase for temperature below T g , but decreases and levels off exceeding this temperature. The increase of activation energy was already shown in former studies by means of DSC measurements with different heating rates [60][61][62] and dilatometer experiments combined with synchrotron measurements [13]. Changes in the activation energy mean a change in the deformation behavior.…”

Influence of niobium and yttrium on plastic deformation energy and plasticity of Ti-based amorphous alloys

“…amorphous alloys. Researchers have proposed changing the crystallization mode of amorphous alloys by adding elements, such as Ag, Pd, Au, Pt, or Y [11,12] ; precipitating quasicrystals or nanocrystals in an amorphous matrix through an annealing process; generating ductile phase dendrites in situ from the amorphous matrix by adding high melting-point elements, such as Ta and Nb in amorphous alloys [13][14][15][16][17] . The second phase in ductile phase dendrites interacts with the shear bands to limit the shear slip of the amorphous matrix on its maximum shear stress surface, and improves the plastic deformation ability of the bulk amorphous alloys [18] .…”

Temperature Rise Inside Shear Bands in a Simple Model Glass

“…The magnitude of temperature rise observed in our simulations can reach roughly five percent of the glass transition temperature, . Noting that the of Zr-based and PdNi-based bulk metallic glasses lie in the range of 500 °K–700 °K [ 27 , 28 ], this would amount to a temperature variation of roughly a few tens of Kelvin, Δ T ≈ 20 °K–40 °K. Even though not too large, such a temperature increase may have important consequences for relaxation processes depending on the operating temperature [ 27 ].…”