Enhanced microhardness in nanocomposite Ti60Cu14Ni12Sn4Ta10 processed by high pressure torsion

Severe plastic deformation of a Ti-based nanocomposite alloy studied by nanoindentation

“…According to EDX measurements (see Table 1) combined with the XRD analyses (see Table 2) the D phase is ascribed to be tetragonal CuTi, with some Ni dissolved in its structure as a substitutional element for Cu, while tetragonal CuTi 2 constitutes the second precipitated phase (C), also with some Ni dissolved. Furthermore, the XRD analyses and the SEM images, in agreement with Woodcock et al [21] and previous work from the authors [9], indicate that b-Ti, cubic NiTi (Pm3m), orthogonal NiTi (Pmma) and monoclinic NiTi (P2 1 /m) compose the eutectic regions. The high cooling rate and the Cu content in the NiTi eutectic phases favour the formation of the NiTi martensitic product phases (orthogonal and monoclinic) from the austenitic parent phase (cubic) [25,26].…”

“…Since the b-Ti reflections are asymmetric, two b-Ti phases were considered in order to fit well the XRD spectra. These two b-Ti phases form the dendrites and one of the phases in the eutectic colonies [2,9] and have slightly different lattice parameters, as recently reported by Woodcook et al through transmission electron microscopy investigations [21]. The higher lattice parameter of the b-Ti forming the dendrites is probably due to the higher amount of solvents, i.e., Sn and Nb (see Table 1).…”

“…Furthermore, few investigations have been performed in the deformation behaviour of composite materials during severe plastic deformation under constrained conditions, such as high-pressure torsion (HPT) [9]. This technique, in which the material is forced to plastically deform without fracture, has been shown to be very effective to induce grain refinement, towards the nanometer scale, and concomitant mechanical hardening in a variety of pure metals [10,11].…”

“…This technique, in which the material is forced to plastically deform without fracture, has been shown to be very effective to induce grain refinement, towards the nanometer scale, and concomitant mechanical hardening in a variety of pure metals [10,11]. We have recently shown that HPT can also induce an important increase in the Vickers microhardness in a Ti 60 Cu 14 Ni 12 Sn 4 Ta 10 nanocomposite alloy [9]. This has been ascribed to the heavy distortion of the dendriteeeutectic microstructure after the application of severe plastic deformation.…”

Synthesis and characterization of nano-structured Cu–Zn γ-brass alloy

“…Among the non-equilibrium techniques developed during the past few decades to synthesize novel materials include rapid solidification processing, mechanical alloying/milling, plasma processing, vapor deposition, ion or electron or neutron irradiation, severe plastic deformation, etc. [3][4][5]. Mechanical alloying which is a solidstate powder processing technique involving repeated cold welding, mechanically activated interdiffusion, fragmentation and dynamic recrystallization of powder particles in a high energy ball mill is an ideal processing route to develop nanocrystalline materials at ambient temperature [6,7].…”