Effect of Fe on the glass-forming ability, structure and devitrification behavior of Zr–Cu–Al bulk glass-forming alloys

Abstract

We report on the glass-forming ability and devitrification behavior of Zr 60 Cu 30 Al 10 , Zr 60 Cu 25 Al 10 Fe 5 and Zr 62.5 Cu 22.5 Al 10 Fe 5 bulk glass-forming alloys on heating. The effect of Fe addition on the structure of Zr-Al-Cu alloys is also discussed. Crystallization kinetics and structural changes in the glassy alloys were studied using X-ray diffraction, transmission electron microscopy, differential scanning and isothermal calorimetry methods. The results indicate that good glass-formers, such as Zr 62.5 Cu 22.5 Al 10 Fe 5 , are located somewhat beyond the equilibrium eutectic point. Possible phase separation in the supercooled liquid on heating and electron beam-induced in situ crystallization are observed and discussed.

Structural relaxation and crystallization processes in Cu55Hf25Ti15Pd5 metallic glassy alloy

“…Rather a binodal-type phase separation has been observed recently in a CueZreAleAg [36,37] and in ZreCueAleFe [38] glassy alloys owing to repulsive interaction in CueAg and CueFe atomic pairs, respectively. In the studied alloy only HfeTi atomic pair having nearly zero calculated mixing enthalpy in a liquid state [39] may be suggested as a reason for the nanoscale separation in Cu 55 Hf 25 Ti 15 Pd 5 glassy alloy, though in general, phase separation is not expected in CueHfeTiePd system as none of the alloying elements have clearly positive mixing enthalpy with each other.…”

Mechanical Properties and Deformation Behavior of Bulk Metallic Glasses

“…This alloy also showed phase separation on heating prior to crystallization [76,131]. Later the Zr 62.5 Fe 5 Cu 22.5 Al 10 BMG samples of 3 mm in diameter and 3 mm in height were cyclically loaded at higher stresses of 800 ± 200 MPa and 1000 ± 200 MPa, which are still significantly lower than the Yield Strength.…”

“…Further investigations on this subject were taken recently and embrittlement of Mg-and La-based alloys is caused by the inclusions of oxides (oxygen is insoluble in solid Mg and La, while it dissolves very well in Zr and Ti) acting as stress concentrators [75]. Zr-Cu-Fe-Al bulk glassy alloy exhibits phase separation on heating prior to crystallization [76], which also may be responsible for its higher room-temperature ductility compared to Zr-Cu-Al alloys.…”

Unusual solidification behavior of a Zr–Cu–Ni–Al bulk glassy alloy made from low-purity Zr

“…In some Zr-based alloys studied earlier, e.g., in Cu 36 Zr 48 Al 8 Ag 8 [40] and Zr 62.5 Cu 22.5 Al 10 Fe 5 [41] glassy alloys, it was noted earlier that these alloys undergo partial nanocrystallization after prolonged observation in the TEM. In contrast, the present alloy seems to be quite stable and no beam effects of crystallization were observed.…”