Quantitative phase evolution during mechano-synthesis of Ti–Ni–Cu shape memory alloys

Abstract

a b s t r a c tTi-41Ni-9Cu shape memory alloy was synthesized by mechanical alloying of pure elemental Ti, Ni, and Cu powders using high-energy ball milling. The qualitative and quantitative phase analyses of the asmilled powders were done by X-ray diffraction (XRD) using Rietveld refinement and the alloys microstructure was studied by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). Concerning the results, by milling evolution, the dissolution of the primary materials occurred at different rates and a considerable amount of the amorphous phase as well as B19 0 -martensite and B2-austenite was created. The formation of Ni solid solution was also evidenced prior to its dissolution. It was found that at sufficient milling time, the mechano-crystallization of the amorphous phase occurred and at the end of milling, the B19 0 -martensite is the dominant phase of the structure.

Effect of milling time on the structure, micro-hardness, and thermal behavior of amorphous/nanocrystalline TiNiCu shape memory alloys developed by mechanical alloying

“…According to the quantitative phase analysis results presented in detail in our previous paper [25] and also listed in Table 2, the existence of stress-induced martensite (SIM, B19 0 ) and B2 austenite is revealed even at short milling times (12 h), which can be due to severe plastic deformation and temperature rising during the milling cycle, respectively. In the XRD patterns of Fig.…”