Cu precipitation in AlCuAl2O3 metal matrix composites

On the transformation behaviour of NiTi particulate reinforced AA2124 composites

“…The frequency of free oscillation decreases monotonically with temperature while the background damping increases. A similar increase in internal friction intensity was also reported in AlCu-Al 2 O 3 and Al/NiTi-fiber reinforced composites, in which the authors related the increase in damping to the presence of a higher density of mobile dislocations [45] and the stiffness difference between NiTi and the matrix [9].…”

“…2) show that the presence of NiTi particulates causes an acceleration in aging kinetics. Such acceleration in precipitation kinetics for identical heat treatments has been reported earlier [39,45,[48][49][50]. However, it was found that this acceleration depends on the aging temperature and became absent for aging temperature below 423 K [50].…”

“…The fact that peak P rel was not observed in the unreinforced material relates it to the presence of NiTi particulates. This peak has been observed earlier in aluminium matrix composites and NiTi SMAs and has been related in both cases to the presence of dislocations [30,32,[45][46][47]. The A → R transformation is characterised by a sharp peak (P R ) accompanied by a drop in the apparent shear modulus (Fig.…”

“…5a, the unreinforced sample exhibits a well-developed peak which corresponds to Zener peak (P1 around 500 K), characteristic for Cu retained in solid solution. Another low intensity peak which is attributed to the GPB zone formation [45] was detected in the unreinforced sample at a temperature about ∼350 K, but disappeared on subsequent cooling. Addition of NiTi to the aluminium matrix resulted in a strong increase in damping intensity and appearance of broad peak P2, which is associated with the presence of S phase.…”

Internal friction peak and damping mechanism in high damping 6061Al/SiCp/Gr hybrid metal matrix composite

“…On the other hand, the mechanical spectroscopy technique is very sensitive to the microstructure state of the sample and it is quite suitable for the study of defects and their interaction processes in the materials. In MMCs, the damping peaks at different temperatures have been used to investigate the micro-mechanisms of thermal stress relaxation [6,7], the particulate/matrix interface [8], the effect of thermo-mechanical behavior on the damping [9] and the precipitation sequence [10]. The medium temperature damping peak in 6061Al/SiC p MMC has been reported [11,12], however, the interpretation of this peak is still not completely clear owing to its complexities.…”