A multilayered hybrid Al1050/AZ31/Al1050 alloy was fabricated by cross-accumulative roll bonding (CARB) up to 5 cycles at 400 °C. Microstructure, anelastic, and mechanical properties were characterized using scanning electron microscopy (SEM), internal friction (IF) measurements, and tensile tests, respectively. The thickness of AZ31 layers of the initial sample gradually loses its continuity in the form of localized necking and fragmentation and reduces to less than 150 µm after the fifth cycle and, contrarily, that of the Al1050 layer increases. Hot CARB processing causes an enhanced formation of intermetallic compounds. For almost all the cycles, apart from N = 1, the ultimate tensile strength of the sandwich measured in the transverse direction is comparable to that of the rolling direction. A maximum value of 182 MPa is achieved after one cycle in the transverse direction and a ductility of 9

Mn-Cu binary alloys with high manganese content exhibit enhanced damping capacity, a broader temperature window for noise and vibration reduction, and low cost. However, they are significantly hindered by poor workability, elongation, and corrosion resistance. To enhance the poor workability, elongation, and corrosion resistance of high manganese Mn-Cu binary alloys, alloying with Cr is an effective approach. This work investigates microstructure evolution, amplitude-independent thermally-activated, and transient effects (in a temperature range from -90 degrees C to 200 degrees C and frequencies from 0.1 Hz to 10 Hz) in high manganese Mn-(10-13) Cu-(0-6)Cr alloys with different Cr contents. The relaxation activation energy for as-water quenched Mn-13Cu binary alloy is 0.56 +/- 0.05 eV. The substitution of Cu or Mn by Cr results in an increase in the activation energy. Phase transitions upon heating and cooling are characterized by modulus softening due to shear phase transition in all analyzed samples before and after ageing, while the transient internal friction peaks are observed not in all structural states. An increase in the volume effect of phase transition leads to an increase in the transitory peaks width and area under the peaks in Mn-10Cu-4Cr compared with Mn-13Cu.

Internal friction and Young’s modulus were measured for pure iron and a high carbon steel. Temperature dependent measurements in pure iron show a strain dependent component to internal friction below the Curie temperature. It can be attributed to the magneto-mechanical damping as confirmed by amplitude dependent measurements at room temperature with and without magnetic field. The bcc to fcc phase transition on further heating is clearly marked by internal friction peaks in both iron and steel. The effects of cementite dissolution and precipitation in steel are visible on thermal cycling at even higher temperatures.

In this paper, the effect of grain size of metastable D0 3 and D0 19 phases in rapidly cooled Fe-27at.%Ga alloy on their transition to equilibrium L1 2 phase at instant heating is studied using temperature dependent internal friction with additional support of neutron diffraction and SEM-EBSD methods. Using two alloys with a similar chemical composition, we demonstrated for the first time that a decrease in the grain size of metastable D0 3 phase, which was achieved by annealing at different temperatures followed by subsequent water quenching, leads to a faster transition to equilibrium state, i.e. that the D0 3 to L1 2 transition takes place at a lower temperature. The D0 19 to L1 2 transition takes place at a significantly higher temperature exhibiting better stability of overcooled D0 19 with respect to the D0 3 phase.

In this paper, transient effects due to different diffusion-controlled phase (in Fe-Ga alloys) and structural (in Al and Cu alloys) transitions are collected and analyzed. In contrast with well-known transient anelasticity due to diffusionless (martensitic) transitions, transient anelasticity for diffusion-controlled transformations has got much less attention in the literature, most probably due to its weaker effects compared with the sharp transient peaks found in martensitic transitions. In this paper, we consider two types of materials and two types of transient anelasticity. The first group of anelastic effects (transient internal friction peaks) that are analyzed in this paper is associated with reversible and irreversible phase transitions in polymorphic Fe-Ga alloys (bcc-, fcc-and hcp-derived structures: D0 3 → L1 2 → D0 19 → B2/A2), and the second one – by recrystallization (internal friction ‘pseudo’ peaks) in several mainly non-ferrous Al-and Cu-based alloys without polymorphic transitions. It is demonstrated that the main features of existing approaches for transient anelasticity due to martensitic transitions can also be applied to anelastic effects in diffusion-controlled transitions, while quantitative values in these models are significantly different from those for shear transition as they are dependent on diffusion processes.

The current research is devoted to microstructure evolution, recrystallization behavior and superplasticity of an Al-Mg-Fe-Ni-Mn-Cr-Zr alloy processed by different routes: hot and cold rolling, friction stir processing (FSP), and friction stir processing followed by rolling. The alloy exhibits a bimodal particle size distribution with coarse Al9FeNi and Al6(Fe,Mn) solidification-originated phases and fine Mn-, Cr-, and Zr-bearing dispersoids. Elongated deformed grains after rolling and a partially recrystallized grain structure after FSP are formed. Mechanical spectroscopy analysis helps to identify a ‘pseudo’ peak associated with recrystallization during heating and a frequency-dependent relaxation peak attributed to grain boundary relaxation during cooling for all studied treatments. Due to both particle-stimulated nucleation (PSN) and Zener pinning effects, the studied alloy exhibits a grain size of 5-6 μm after elevated temperature annealing. FSP refines coarse particles from 1.0 to 0.4 μm and leads to a less homogeneous size distribution of coarse particles than hot rolling. Grain size stability and superplastic behavior directly depend on the treatment regimes. Due to a thermally stable grain structure up to the sub-solidus temperature of 540 °C, the hot and cold rolled alloy exhibits elongations to failure of 300-400

In this study, the Mg-0.8Mn (M08, wt%) alloy is subjected to hot extrusion at various temperatures ranging from 150 degrees C to 300 degrees C, and the correlations between the microstructure evolution, tensile properties, and work hardening behavior at ambient temperature are elaborated. The M08 alloy extruded at 150 degrees C exhibits a bimodal microstructure, which included undynamic recrystallized (unDRXed) grains and fine dynamic recrystallized (DRXed) grains with an average size of 1.4 mu m. As the extrusion temperature exceeds 210 degrees C, fully DRXed grains can be observed with grains growth becoming more pronounced with the increase of extrusion temperature. Notably, Mn atomic segregations are evident at the grain boundaries (GBs) in the M08 alloy extruded at 150 degrees C. It is also essential to highlight that the propensity for GB segregation is diminished with higher extrusion temperature, and the amount of alpha-Mn precipitates within grain interiors is increased in the M08 sample extruded at 300 degrees C. An intriguing observation is the abnormal rise in yield strength (YS) with grain size as the extrusion temperature is increased. This phenomenon can be attributed to the diminishing effect of GB sliding and the concurrent enhancement of GB strengthening effect. However, as the extrusion temperature is raised from 150 degrees C to 300 degrees C, the ductility of M08 alloy experiences a substantial decline from 74 % f 4-16 % f 3 %. Meanwhile, the grain growth can bring about an increased strain hardening rate, which is primarily dependent on the transition in the dominant deformation mechanism from grain boundary sliding (GBS) to dislocation slip. This transition leads to a more substantial accumulation of dislocations within the coarser grains, thereby affecting the mechanical behavior of M08 alloy. This work provides valuable insights into the influence of extrusion temperature on the microstructure evolution and mechanical properties of Mg-0.8Mn alloy, offering a foundation for optimizing the processing parameters to achieve desired mechanical performance.

Analysis of electrical resistivity at first-order transitions (L12 -> D019 -> B2) was for the first time conducted in the Fe-28.1%Ga alloy during heating, cooling, and at isothermal annealing. Phase transitions and alloy structure were additionally controlled in situ using neutron diffraction. The Avrami parameter for the reverse L12 <-> D019 transitions under isothermal conditions was calculated, with an analysis of the morphology of the growing phases conducted similarly to that of the L12 <-> D019 transition in the Fe-26.9Ga alloy from our previous study. The L12 + D019 phases coexistence interval in the Fe-28.1Ga alloy is determined to span 600-615 degrees C, and is in agreement with the phase diagrams proposed by Kubaschewski. The B2 -> D019 and D019 -> L12 transition kinetics vary greatly depending on instant cooling rates.

Stress-assisted atomic diffusion behavior in NiTiHf shape memory alloys was investigated by measuring the internal friction at temperature range of 300-1070 K. A thermally activated internal friction peak was recorded in the B2-ordered phase in the temperature range of about 850-950 K (at 1 Hz, depending on alloy composition), with activation energy of 1.79 +/- 0.05 and 2.00 +/- 0.10 eV and relaxation time of 2.7+1 -2 center dot 10-12 and 1.7+1-5 center dot 10-13 s for Ni50Ti35Hf15 and Ni50Ti30Hf20 alloys, respectively. It was proposed that the short-range diffusion of Ni-atoms under the stress is the main relaxation mechanism in the studied alloys. The diffusion coefficients of Ni in the B2-ordered phase were estimated to be 3.72 & sdot;10-8 and 5.90 & sdot;10-7 m2s- 1 for Ni50Ti35Hf15 and Ni50Ti30Hf20 alloys, correspondingly.

Analysis of the first-order transition between D03 and two close-packed phases (L12, D019) in Fe3Ga-type alloy (26.9 %Ga), is carried out at different cooling rates from the range of equilibrium D019 phase and at different cooling rates from the range of equilibrium A2 phase. The structure was controlled by neutron diffraction, SEMEBSD and additionally characterized using VSM and ATP tests. The obtained results clarify kinetics of D019 phase growth and transition to low temperature equilibrium L12 phase. We demonstrated that D019 phase is ferromagnetic at room temperature with very low saturation magnetostriction.

Effect of recrystallization in Al-,Cu-,Mg-,Ti- and Ni-based alloys on temperature and amplitude dependent damping of forced mechanical vibration measured by DMA Q800TA Instruments is analyzed. Different annealing regimes such as instant and interrupted heating, isothermal annealing are proposed. Formation of pseudo recrystallization internal friction peak is discussed.

The evolution of the structural phases of the Fe-42.4 at% Ga alloy was studied using neutron diffraction performed with high-intensity continuous scanning in a wide temperature range. The sequence of occurrence of structural states both during heating and subsequent cooling is reported. The structural phases Fe13Ga13, Fe13Ga9, alpha-Fe6Ga5, D03, L12, A2 are present in the alloy and they disappear upon heating above 800 degrees C into the partially ordered B2/A2 phase. The high-temperature Fe13Ga13 intermetallic compound exists in two temperature ranges: 25-580 degrees & Scy; and 770-800 degrees & Scy; during heating and precipitates again during cooling. The persistence of the phase upon cooling down to room temperature is inconsistent with the phase diagram, indicating that the alloy remains in a metastable state after the heating and subsequent cooling. The D03, alpha-Fe6Ga5 and L12 phases are formed during cooling.

Anelastic relaxation in the temperature range from 0 to 300°C (0.1-30Hz) in ternary Fe-26(Al+Ga)-0.1Tb alloys is experimentally studied and analysed with respect to binary Fe3Al and Fe3Ga intermetallic compounds. The Snoek-type relaxation due to cyclic stress-induced carbon atom jumps between octahedral interstices in the α-Fe based solid solution (Fe-C-Al,Ga) is recorded and analysed. The Snoek-type effect in the ternary Fe-26(Al+Ga)-0.1Tb alloys has a higher activation energy (up to ∼1.2eV) in comparison to α-Fe-C (0.83eV). The relaxation effect demonstrated significant broadening with respect to Debye peak with a single relaxation time and splitting into two separated peaks at a certain ratio Al/Ga. Snoek-type effect provides a unique opportunity to measure C atom diffusivity at relatively low temperatures. Influence of the chemical composition and the measuring frequency on the activation parameters in Fe-26(Al+Ga)-0.1Tb alloys are reported and analysed to estimate the impact of Al and Ga atoms on C atom diffusivity in α-Fe based solid solution.

Anelastic relaxation at sub-resonance frequency (from 0.01 to 100Hz), temperature (from 0 to 450°C) and amplitude (ε0 from 5×10-5 to 10-3) range in binary Mg-0.8wt.%Mn (0.36at.%) and Mg-2wt.%Gd (0.31at.%) in as-extruded and annealed states was experimentally studied and analyzed, to characterize acting thermally activated and structural relaxation effects. Activation parameters for thermally activated anelastic effect and structural studies suggest that it is the grain boundary relaxation with dominating large angle boundaries, while the high-temperature background is mainly controlled by dislocations sliding. Pseudo peak at ~290 °C (Mg-Mn) and ~410 °C (Mg-Gd) is the result of the recrystallization process in the as-extruded samples, which indicates that the addition of Gd restricts the recrystallization of Mg compared with the addition of Mn. Analysis of amplitude dependencies of internal friction in the frames of Granato and Lücke approach suggests higher density of movable dislocations in as-extruded Mg-Mn alloy.

The formation of nanoprecipitates in the Fe81Ga19 alloy doped with Tb (similar to 0.1 at. %) was studied by small-angle neutron scattering (SANS). Measurements at room temperature for several samples pre-aged at a fixed temperature in the range of (300-700)degrees C revealed a dilute system of precipitates with a characteristic size at nanoscale (<1000 & Aring;) growing with an increase in ageing temperature. In situ measurements during isothermal ageing at 300 degrees C for 3 h revealed fast (order of 10 min) formation of precipitates. SANS analysis is consistent with the results of neutron diffraction experiments, which suggest the microstructure of this alloy as a matrix of disordered atomic structure (A2 phase) with embedded precipitates of the structurally and magnetically ordered D0(3) phase.

An analysis of the first order transition kinetics between D03 and L12 phases in Fe3Ga-type alloy is carried out. Structure and magnetostriction of the samples were carefully controlled by SEM-EBSD analysis and magnetostriction tests after different heat treatments, and additionally in in situ regime by VSM and DSC. C-shaped curves for time-temperature-transition (TTT) diagram based on the results of the EBSD analysis of Fe-27Ga alloy are constructed in the temperature range between 400 and 550 degrees C. TTT diagram shows that the nucleation rate for L12 phase increases in the sequence 400 -> 475 -> 550 degrees C, while the growth rate reaches a maximum at about 500-525 degrees C. Effect of D03 <-> L12 thermocycling on the kinetic of the D03 -> L12 transition is studied for the first time. The amount of the L12 phase after sample re-quenching and subsequent annealing at the same annealing temperature and time, significantly increases compared with the first cycle quenching and subsequent annealing, demonstrating memory effect of previous transitions.

Currently, the dominant model for the formation of enhanced magnetostriction of Fe-Ga alloys is based on the assumption of the presence of microscopic inclusions with a tetragonal L60 structure in the cubic matrix of the alloy. However, no evidence for the presence of this phase in the bulk of the alloys in amounts sufficient to have a noticeable effect on the magnitude of magnetostriction has been obtained so far. To test this hypothesis, a detailed scanning of the reciprocal space of Fe81Ga19Tb0.1 and Fe73Ga27 single crystals was carried out at ESRF at high photon flux stations. In particular, it was possible to reliably record superstructure diffraction peaks, the intensity of which was at a level of 2 x 10-6 from the intensity of the fundamental peaks. Nevertheless, neither the presence of superstructure diffraction peaks obviously belonging to the L60 phase nor the tetragonal splitting of the fundamental diffraction peaks into components, which could indicate the presence of this phase in the samples, was detected. Similar results were obtained using complementary methods (electron and neutron diffraction). Based on the performed analysis of the background level in the places of the expected positions of superstructure peaks of the L60 phase, it was found that the volume fraction of this phase in the Fe81Ga19Tb0.1 alloy cannot exceed 0.2%. The presence of a previously discovered X phase with hexagonal or orthorhombic symmetry in a crystal with 27 at. % Ga was confirmed.

New data on phase states and structural phase transitions in alloys Fe73Ga27 doped with Dy, Er, Tb, and Yb in an amount of about 0.5 at

The results of high-precision electro-resistivity measurements, rho(T), for Fe-18.5%Ga alloy over a wide temperature range are presented. An anomaly in the rho(T) temperature behavior is detected and it is proved that it correlates well with the change in the unit cell lattice parameter of the alloy and with the results obtained from measuring magnetization, dilatometry and positron annihilation. From the neutron diffraction data, it follows that the detected anomaly is associated with the formation of a cluster-like microstructure of the alloy: in the structurally disordered A2 matrix, regions with partially ordered D03 phase are formed. Interpretation of this non-monotonic behaviour of rho(T) is discussed.

Phase transitions between structurally ordered phases in Fe-Ga alloys have been studied upon their heating to 850 C and subsequent cooling to room temperature by neutron diffraction in real-time mode. The transitions between four types of phases have been analyzed: D03 -> L12 (both cubic phases), L12 F iota D019 (cubic - hexagonal), D019 F iota A2 (hexagonal - cubic). It has been established that all phase transitions include stage of the formation of a disordered state and have a combined, diffusive-displacive nature. The diffusion stages are necessary for the disordering and ordering of the structure, the displacive stage provides a change in the type of the crystal lattice. It can be concluded that the formation of an intermediate disordered state followed by a transition to the final equilibrium state is less energy-consuming than the direct transition to the final state. During the observed transformations, no traces of predicted intermediate structurally ordered tetragonal phases were found. These results may provide new insight into the microscopic basis for the formation of enhanced magnetostriction in Fe-Ga alloys.