Figure 1

Schematic representation of the martensitic transformation of an AB alloy with subsequent martensite aging according to the SC SRO model. The transformation (1) from the high symmetry (a) to the martensite phase (b) is diffusionless and happens on very fast time scales. If the sample is held at a fixed temperature the transformation may occur or proceed after a certain incubation time. Subsequently, the diffusive aging process (2) rearranges the average defect arrangement until it corresponds to the reduced symmetry (c). The two colors represent atoms A and B, respectively, and their proportions indicate the probability of finding an atom of type A or B at the respective position. See 11, 13 for further details.Reuse & Permissions

Figure 2

(a) Schematic setup for x-ray photon correlation spectroscopy measurements in Bragg geometry. See text for details. (b) Diffraction image of the (0 0 1) Bragg reflection summed over 30 exposures at temperatures of 330 K and $305.3\mathrm{K}=M_{\mathrm{s}}-0.05\mathrm{K}$ (c). The white markings in the high temperature image show the regions where the low temperature Bragg reflections will be located. The intensities of these regions vary gradually with temperature until the diffraction image changes drastically at the transformation temperature. In both pictures the circle indicates the region of interest for which the correlation functions are calculated and the black dots indicates the center of the Bragg reflection defined by the highest intensity pixels. The $q$ values have been calculated with respect to this reference. The $q_z$ and the logarithmic color scales apply to both images.Reuse & Permissions

Figure 3

One-time correlation functions at temperatures close to the martensitic transformation. At temperatures higher than $M_s=305.35\mathrm{K}$ the correlation functions show compressed behavior but at temperatures below $M_s$ the behavior is almost exponential. The solid lines represent fits to the data.Reuse & Permissions

Figure 4

(a) Two-times correlation function $C_2$ at a temperature of 305.3 K calculated via Eq. (4) for a circular region with a radius of 50 pixels around the center of the high temperature Bragg reflection. Note the divergent color contours showing non-equilibrium dynamics and the sharp-cut divisions in several rectangles due to avalanche dynamics. The latter is caused by avalanches in the sample occurring at 65, 89, 285, and 798 s. The black dots indicate the starting times of the extracted one-time correlation functions. (b) Time scales ${\tau }_0$ and corresponding KWW exponents $\beta$ extracted from one-time correlation functions or—in the case of 305.3 K—from the two-times correlation function at specific times marked in (a). See text for details.Reuse & Permissions