Modification of Corrosion and Mechanical Behaviour of Cu-Zn-Al Shape Memory Alloy

Abstract

Abstract shape memory alloys (SMAs) exhibit an interesting research topic. The currentss limitationss to thes SMAsss is thats the cost of SMAss, mades outs ofs expensive elements such as Ni and Ti. In this work, the influence of different amount of nickel (Ni), boron (B), and boron oxide (B6O) additionss ons the structure, mechanicalss, electrochemical, and tribological behaviourss of Cu - Zn - Alss SMAsss have been investigateds. Cu–25Zn–4Al SMAs were produced by powder metallurgy technique with and without the addition of 0.5, 0.7, and 1 wt.% of Ni or B. After mixing the powders for 4hr, the alloys were prepared using 675MPa compact pressure. The alloys were subjected to sintering process in vacuum tube furnace with three stepsss. For microstructural and phases characterisation of alloyss withs and withouts the additions of elements (Ni, B), optical microscopy (OM), scanningss electronss microscopyss (SEM), and XRD diffractions analysiss weres carrieds outs. The transformation temperatures of alloys with and without the addition of elements (Ni, B) were measured by differentials scannings calorimetrys (DSC). The shape memory properties of alloyss withs and withouts the additions of elements (Ni, B) were investigated using shape memory effect test (SME). Electrochemical corrosion tests for alloys with and without the addition of elements (Ni, B) were carried out using potentiodynamic polarization technique. XRD and microstructural analysis showed that all alloys compositions consisted of the predominating Cu5Zn8 phase. The results of transformation temperatures showed that the Ni and B additions have strong influences ons the transformations temperaturess of Cu – Zn – Al SMAs. The results of electrochemical corrosion tests showed that an increased in Ni or B content up to 1wt. % improved the corrosions resistances of the unmodified Cu – Zn – Als SMA in 3.5 NaCls. In the second part, the influence of different amount (1,3, and 5 wt. %) of boron oxide (B6O) additionss ons the mechanicalss and tribology properties of Cu – Zn – Als SMAsss with the addition of 1wt.% Ni or 1wt.% B has been investigated. s Hardness measurements was usedss to assessss the mechanicalss propertiesss of 1, 3, and 5 wt.% B6O modified Cu – Zn – Al – Ni or Cu – Zn – Al – B alloy compositions. Wet sliding wear process was investigated for 1, 3, and 5 wt.% B6O modified Cu – Zn – Al – Nis or Cu – Zn – Als – B alloy compositions in distilled water at 2, 5, and 10 N normal load at room temperature. The resultss of hardness measurements show that an increase in B6O content up to 3 wt.% improved the hardness of Cu – Zn – Als – Ni and Cu – Zn – Als – B SMAss. The tribological results show that the wear resistance of Cu – Zn – Als – Ni and Cu – Zn – Al – B SMAs exhibiteds the best results with 3 wt. % of B6O addition. Further increase or decreases of B6O contents decreases the wears resistances of the alloys.