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Efect of heat treatment parameters on microstructure evolution, tensile strength, wear resistance, and fracture behavior of Ni-Ti multilayered composites produced by cross‑accumulative roll bonding

Ye Qing, Li Xuejun, Tayyebi Moslem, Assari Amir Hossein, Polkowska Adelajda, Lech Sebastian, Polkowski Wojciech, Tayebi Morteza

Archives of Civil and Mechanical Engineering

2023

Vol. 23, no. 1

art. no. e27, 2023

The last decades have seen a huge growth in the investigation of intermetallic compounds at the interfaces of laminated composites due to their useful features. In this research, efects of the formation of intermetallic compounds on tensile properties and wear resistance of Ni/Ti composites produced by cross-accumulative roll bonding (CARB) process have been examined at diferent annealing times and temperatures. Scanning electron microscopy (SEM) images demonstrated that the layers were well bonded together, but Ni layers experienced instabilities in light of plastic deformation. The EBSD results showed lamellar structure and crystallographic texture on Ti and Ni layers during plastic deformation. According to X-ray difractometer (XRD) and energy-dispersive spectrometer (EDS) analyses, NiTi2 and NiTi were present in all annealed samples. The thickness of intermetallic compounds grew with an increase in annealing temperature and time. However, this growth led to a decrease in tensile strength while the values of elongation fuctuated. Based on the results of the wear test, the composite became more resistant to wear when the thickness of intermetallic layers increased. The surfaces of these layers with less roughness and lower coefcients of friction facilitated the movement of steel pin on samples during the wear test. Furthermore, wear mechanisms of adhesion, abrasion, and delamination were observed, and they were more noticeable at higher loads and lower annealing temperatures and times.

Post-fire impact behavior and durability of steel fiber-reinforced concrete containing blended cement-zeolite and recycled nylon granules as partial aggregate replacement

Nematzadeh Mahdi, Nazari Ali, Tayebi Morteza

Archives of Civil and Mechanical Engineering

2022

Vol. 22, no. 1

art. no. e5, 2022

Recycling polymeric waste in concretes to replace a portion of the stone aggregate volume can improve some of the mechanical features of concrete such as impact resistance, while also helping mitigate the associated environmental problems. Thus, this research was aimed at exploring the combined effect of nylon granules (0, 10, and 20%) as a replacement for fine aggregate, steel fibers (0, 0.75, and 1.25%), and zeolite (0, 10, 15, and 20%) as a replacement for cement on the impact resistance and durability of concrete following several heating levels (20, 300, and 600 °C). For this purpose, 432 concrete samples were manufactured, and the concrete features including compressive strength, tensile strength, impact resistance, loss of weight, water absorption, porosity, density, and failure type of concrete samples after different heating levels were investigated. The results demonstrated that the impact energy at the failure level declined considerably with temperature for all the concrete samples containing nylon granules and steel fibers (by 46–94% for 600 °C). However, increasing nylon granule content to 20% in concrete improved the impact resistance at the first and ultimate crack levels following exposure to 20 and 300 °C, while significantly lowering this parameter (by up to 40%) following exposure to 600 °C. Furthermore, the inclusion of steel fibers in concrete and increasing its content led to increased impact energy of the heated and non-heated concretes.