The impact of micro-alloying on relaxation dynamics in Pd40Ni40P20 bulk metallic glass

Abstract

The impact of Co micro-alloying on low temperature specific heat capacity and the relaxation processes in a model Pd40Ni40P20 bulk metallic glass in both as-cast and cold-rolled states was investigated. In addition to an excess (Boson) peak at low temperatures of about 12 to 14 K, a magnetic heat capacity anomaly in the Co alloyed glass below 10 K was observed. The measured Boson peak heights and the fictive temperatures both advocate a much faster β relaxation in the micro-alloyed glass. Yet, the micro-alloying does not measurably affect the enthalpy associated with α-relaxation. The impact of shear bands on the thermodynamic properties of the micro-alloyed glass is discussed.

Exploring the Phase Space of Multi-Principal-Element Alloys and Predicting the Formation of Bulk Metallic Glasses

“…To investigate the impact of small concentrations of an additionally added element on a glass-forming alloy, the critical cooling rates and glass formation regions are computed for the Pd-Ni-P-system micro-alloyed with 1 at% of Co, Cu, Fe, and Gd. Micro-alloying of Co, Cu, and Fe had little effect on the overall glass-forming ability which matches well with experimental results for (Pd 40 Ni 40 P 20 ) 99 Co 1 and (Pd 40 Ni 40 P 20 ) 99.4 Fe 0.6 that showed an impact on the mechanical properties without affecting the glass formation properties in a significant way (see Figure 6) [28,29].…”

Impact of Severe Deformation by HPT at Room Temperature on the Relaxation of the Glassy and the Supercooled Liquid States of PdNiP

“…All measurements shown are baseline corrected. Moreover, it is worth noting that the glass transition temperature T g is defined here as the temperature at which the integrated heat release corresponding to the supercooled liquid equals that of the relaxation state 13,38 . Relaxation experiments were performed under Ar atmosphere via isothermal holding in the DSC at 561 K for 2 hours.…”

“…The characteristic low-temperature anomaly of the specific heat capacity in glasses is termed "boson excess peak" 42,43 . Plotting C Ph p /T 3 versus T reveals the deviation from the Debye-like behavior at low temperatures due to scattering of the quasi-phonons of the glass at structural heterogeneities 2,13,39,40,44 .…”

“…II is in good agreement with a former report 12 . Moreover, the shift in T g , here defined via the half-c p method 13 , is an indicator that the individual relaxation state is influenced by both defor-mation (∆T g = 5/6 K -see black and blue as well as red and purple curves in Fig. 1) and annealing (aging: ∆T g = 7/8 Ksee black and red as well as blue and purple curves in Fig.…”

“…Thus, the structure of the glassy material was modified by severe plastic deformation leading to an increased heterogeneity [76][77][78][79][80] , in which different arrangements of atoms or clusters in space locally produce an increased amount of excess free volume 2,40 . However, structural aging/relaxation generally leads to a decrease in the boson peak height 12,13 . Strikingly, the present PPMS results revealed congruent boson peak curves after annealing the "10 HPT" and "as-cast" states (see Fig.…”