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The influence of thermal-deformation history on the evolution of secondary phases in P91 steel annealed at 853, 893, and 923 K was studied by means of transmission electron microscopy. Calculations of phase equilibria for a Fe–Cr–V–Mo–Ni–Nb–Mn–N–C system corresponding to the investigated steel were also carried out. The calculations were performed using the thermodynamic database program Thermo-Calc. M23C6 and MX phases were identified experimentally in all conditions investigated. Laves phase was only found in conditions annealed for longer times at 853 and 893 K and in the non-deformed condition annealed at 923 K per 1000 h. The thermodynamic calculations revealed M23C6 and MX as equilibrium phases at 853, 893, and 923 K. The discrepancy between experimental and calculated results concerning the Laves phase indicates that either the investigated steel has not achieved equilibrium after aging for 5000 h at 853 and 893 K or the thermodynamic model for this phase should be modified. Also the temperature dependencies of the Cr/Fe ratio for M23C6 carbide showed opposite tendencies for originally deformed and non-deformed conditions. [Copyright &y& Elsevier]

The work is focused on the experimental reinvestigation of the Al–Co phase diagram in vicinity of the Al 13 Co 4 family of phases. For this purpose several alloys were prepared with bulk compositions ranging between Al 71 Co 29 and Al 77 Co 23 . Experimental samples processed of the as-cast alloys were annealed for 330 h at various temperatures between 1070 and 1150 °C and subsequently rapidly cooled to fix their high-temperature microstructures. The annealing temperatures were selected with respect to the earlier published Al–Co phase diagrams. In the investigation X-ray diffraction, differential scanning calorimetry, and scanning electron microscopy including both energy dispersive X-ray spectroscopy and electron backscatter diffraction were used. In the microstructures of as-annealed alloys various combinations of B2-AlCo, Al 5 Co 2 , Z-Al 3 Co, Y 1 -Al 13 Co 4 , Y 2 -Al 13 Co 4 , M-Al 13 Co 4 , O′-Al 13 Co 4 , and solidified liquid were identified. It was found out that the earlier published single-phase Y-area is comprised in fact of monoclinic Y 1 -Al 13 Co 4 and orthorhombic Y 2 -Al 13 Co 4 lamellas. From the thermodynamic point of view, Y 1 -Al 13 Co 4 and Y 2 -Al 13 Co 4 are stable and metastable phases, respectively. The O′-Al 13 Co 4 phase was identified at 1070 °C in the alloys where the occurrence of O-Al 13 Co 4 was expected. A modified partial Al–Co phase diagram was also proposed with respect to the experimental results obtained. [ABSTRACT FROM AUTHOR]

Abstract: The originally as-cast Al55Ni30Pd15 alloy was investigated during continuous heating from room temperature to 600 °C and after annealing at 600 °C for respective 455, 2650, and 4050 h. In the investigation the synchrotron X-ray diffraction and the high-resolution scanning electron microscopy inclusive of the energy-dispersive X-ray spectroscopy were used. In all the investigated conditions β-(Ni,Pd)Al (Pm3m) and Al3(NiPd)2 (P3m1) phases were identified. After 2650 h of annealing the former phase was found to be separated into two isostructural modifications differing from one another in Pd- and Ni-contents. The annealing for 455 h contributed to the decrease of lattice parameters in the Al3NiPd phase compared to the original as-cast condition. [Copyright &y& Elsevier]

Abstract: The Al68Pd14.6Co17.4 and Al69.8Pd13.8Co16.4 alloys were investigated after continuous cooling and/or annealing at 700 °C for 2000 h. In the investigation light microscopy, scanning electron microscopy including energy dispersive X-ray spectroscopy, X-ray diffraction, electron backscatter diffraction, and differential thermal analysis were used. In the as-annealed near-equilibrium conditions of the Al68Pd14.6Co17.4 and Al69.8Pd13.8Co16.4 alloys U + β + Al5Co2 and U + Al5Co2 were identified, respectively. The U-phase in a majority of investigated samples was found to consist of 2–3 mutations differing from each other in metal composition, but exhibiting the same crystal structure. The mutations showed compositional features of their parent phases (liquid, V, and β). [Copyright &y& Elsevier]

Abstract: The characterization of phases in Al73Mn27−x Fe x (x =2, 4 and 6) alloys was performed using X-ray diffraction, differential thermal analysis, and scanning electron microscopy enabling energy dispersive X-ray spectroscopy. Both the annealed and the thermally cycled states were studied. In the annealed states the occurrence of T-phase was expected, however it was confirmed for alloys Al73Mn25Fe2 and Al73Mn23Fe4 only. The annealing of the Al73Mn21Fe6 alloy probably led to the formation of decagonal quasicrystal (D). The T- and D-phases were found to be unstable at low temperatures. In the states after DTA the low temperature Al11(Mn,Fe)4 and γ2 phases were observed in the Al73Mn25Fe2 and Al73Mn21Fe6 alloys, while only the former phase was observed in the Al73Mn23Fe4 alloy. [Copyright &y& Elsevier]

Alloys with bulk compositions ranging between Al71Co29 and Al77Co23 are prepared by arc melting the elements followed by annealing at temperatures between 1070 and 1150 °C (330 h) and rapid quenching. [ABSTRACT FROM AUTHOR]