Abstract
Resistivity changes of magnetron sputtered, amorphous Cr2AlC thin films were measured during heating in vacuum. Based on correlative X-ray diffraction, in-situ and ex-situ selected area electron diffraction measurements and differential scanning calorimetry data from literature it is evident that the resistivity changes at 552 ± 4 and 585 ± 13 °C indicate the phase transitions from amorphous to a hexagonal disordered solid solution structure and from the latter to MAX phase, respectively. We have shown that phase changes in Cr2AlC thin films can be revealed by in-situ measurements of thermally induced resistivity changes.
Highlights
Cr2AlC belongs to the Mn+1AXn phases, where M is a transition metal, A an A group element and X represents either C or N, a class of nanolaminates which have attracted considerable attention within the last decade due to their unusual combination of properties[1,2]
X-ray amorphous Cr2AlC powder samples synthesized by physical vapor deposition (PVD) have been analyzed by differential scanning calorimetry (DSC) by Walter et al.[24] and Abdulkadhim et al.[25]
Ex-situ structural analysis reveals the formation of the disordered solid solution between 540 °C and 560 °C and a subsequent phase change to Cr2AlC MAX phase in the temperature range from 580 °C to 600 °C
Summary
Cr2AlC belongs to the Mn+1AXn phases, where M is a transition metal, A an A group element and X represents either C or N, a class of nanolaminates which have attracted considerable attention within the last decade due to their unusual combination of properties[1,2]. (Cr,Al)2Cx is structurally similar to the Cr2AlC MAX phase, which was suggested to consist of three perfectly ordered (Cr,Al)2Cx unit cells with a stacking sequence of Cr-Cr-Al-Cr-Cr-Al exhibiting a non-metal sub lattice order of C-vac-vac-C-vac-vac[25]. It is the ambition of this work to detect phase changes by in-situ resistivity measurements during heat treatment. It is shown that these structural transitions result in characteristic resistivity changes which enable remote tracking of phase changes by in-situ resistivity measurements
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