According to a thermodynamic approach, the energy barrier (DG*) to overcome for a homogeneous nucleation from amorphous to crystalline phase is (Lee et al.In this interfacial layer (B in Fig.?According to the previous thermodynamic analysis, the presence of shear stresses increases the compaction of the atoms producing molar volume decreases leading to the reduction of the barrier energy DG*., 2004), considerably reduce the energy barriers for nucleation favoring the formation of nano and micro-crystalline phases. 8) enhancing atomic redistribution in more ordered clusters prone Thermoset polyester resins to crystallization (the elastic compression energy is then stored in the crystalline phase).
In our samples sub-micron size crystal grains are observed in the layer between 20 and 40 microns from the external surface.Following the Potential Energy Landscape theory (Debenedetti and Stillinger, 2001; Klement et al.. 8) two driving forces are acting to induce crystal nucleation, the greater temperature difference from the thermodynamic melting temperature (the interlayer near above the glass transition) and the shorter distance between the crystallizing atoms (intense shear stresses squeeze and compact alloy atoms in a reduced volume, layer B in Fig.ConclusionThe investigations of our research group on new materials and technologies in involving deep understanding of matter and their properties (Aversa et al.These shear stresses, as it occurs for local crystallization in shear bands formed in highly deformed BMG’s (Kanugo et al.
The elastic strain energy induced by the change in volume in the crystallization process (with Ec=(Vma-Vmc)/3Vmc; with E the elastic modulus.This equilibrium glassy inherent structures may, under high shear and compressive conditions, become more compacted (layer B in Fig., 1960), inherent structures, which are associated to energy local minima, are the equilibrium stable glassy states that are divided by energy barriers between the different potential equilibrium configurations.Equally, the near above temperature of the melt increase the value of the free energy DGm lowering the energy barrier for crystallization. 8) favor crystal nucleation and growth
