# Thermal and Thermomechanical Analysis of Amorphous Metals: A Compact Review
## 3 Thermomechanical Characterization of Amorphous Metals
### Possibilities of TMA for Metallic Glass Analysis  
[PERSON] et al. studied the effects of the uniaxial compression of La\({}_{55}\)Al\({}_{25}\)Ni\({}_{20}\)-based glasses under three different loads and analyzed the relaxation processes using FDSC by varying the time after deformation at which the analysis was performed. They concluded that under plastic deformation, the enthalpy of the material increases, but only by a fraction of the mechanical work applied to the samples (\(\sim\)3%), and while this is not unusual for the glassy state of amorphous metals, it is still low compared to, e.g., polymers in their glassy state, which can store, on average, an order of magnitude more energy than glassy metals. By performing stability measurements, they also observed that the stored energy is lost after \(\sim\)24 months in all the samples. However, they proved that mechanical rejuvenation can be as effective as thermal rejuvenation following their previous work [65] (Figure 3).  
[PERSON] et al., however, studied the effects of elastostatic load (EL) and cryogenic thermal cycling (CTC) on the ability to induce rejuvenation in Pd\({}_{43}\)Cu\({}_{27}\)Ni\({}_{10}\)P\({}_{20}\) glasses. In their work, CTC was executed by cooling with nitrogen, while the EL measurements were performed at 85% of the components' yield stress. They observed that neither EL nor CTC have any effect on \(T_{g}\), \(T_{c}\), or enthalpy of crystallization. The experimental data indicated that both processing techniques result in an increase in stored energy. However, thermo-mechanical analysis revealed that this increase does not correspond to rejuvenation. This conclusion is drawn from the different correlations observed between enthalpy and density changes in samples processed using EL and CTC methods compared to conventionally prepared metallic glasses that underwent rapid quenching. Furthermore, they propose  
Figure 3: (**a**) The increase in enthalpy (\(\Delta H\)) after compression at varying degrees of deformation and (**b**) specific heat curves show a shift in thermal behavior of the material with increasing heating rate from 1 to 798 K min\({}^{-1}\) (reprinted with permission via CC Attribution 4.0 License; multiple Figures were merged for a better overview of the authors’ work) [65].  
that the mechanism of enthalpy increase is structurally driven, activated by the shear transformation zones, which possess locally increased entropy (because their deformation is thermodynamically favored) that draws in the heat upon mechanical deformation, resulting in increased stored energy within the material [74]. There are reports on thin films as well, where thermomechanical analysis has proven useful in identifying the best mechanical properties of metallic glass thin films for various applications under thermal load (photo- and thermophotovoltaic and sensing applications) where the interface and morphology play a crucial part in the proper functioning of the device [75; 76]. [PERSON] et al. deposited thin films of tungsten oxide by laser ablation and studied the mechanical properties with annealing. Thanks to the versatility of laser ablation, they were able to reproduce various morphologies, which allowed them to observe the change in total stress as a result of grain growth and diffusion processes, leading to the shrinkage of the material, which can be observed as a change in the slope in Figure 4a. Figure 4b shows multiple moduli that can be monitored as a function of annealing temperature [77].