Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Smart materials


Investigation of Corrosion Behavior for Copper-Based Shape Memory Alloys in different Media

E.S. Al-Hassani; A.H. Ali; S.T. Hatem

Engineering and Technology Journal, 2017, Volume 35, Issue 6, Pages 578-586

Copper based shape memory materials was interesting group of metal alloys that have a widespread potential in medical and industrial application due to their characteristics ,the possibility of exhibiting shape memory behavior and lower cost. In this research the alloy (Cu-(15-40) wt%Zn-6wt.%Al) has been prepared by powder metallurgy technique Zn element (15, 20, 25, 30, 35, 40 wt%Zn) and fixed percentage of Al content which is 6.wt%Al then aluminum replaced by (Si, Sn, Ni )element at fixed percentage of 6wt.%, in order to study the effect of these elements on SMA. After samples preparation examination were done by using XRD, SEM technique, DSC, Vickers hardness, Archimedes method to measure the porosity percentage and corrosion rate in different solutions (HCl, NaOH and SEAWATER).The XRD and microstructure results show that all samples with and without additives consist of two phases (β-phase) and (α-phase) at room temperature and the addition of alloying elements in these percentages does not have effect on present phases. the hardness increased with zinc content because the formation of intermetallic compound of CuZn that responsible to hardness while The addition of Si ,Sn and Ni leads to lower the hardness than aluminum. The bulk density increased with the alloys without addition alloying elements(Si, Ni and Sn ) while apparent porosity decreased with it the reason for this phenomenon due to the characterization of alloying elements that addition to the alloy. From the results of corrosion test can be show the alloy with 35wt% Zn have the higher corrosion resistance in all media (HCl, NaOH and sea water) and the addition of alloying element lead to improve the corrosion resistance. Finally, it is observed that the Copper base shape memory alloys with these types of additives are suitable for use in different application.

Preparation and Characterization of Biomedical Ni-Co-Al Shape Memory Alloys

Emad S. Al-Hassani; Sahib M. Al-Saffar; Zena Abdul Ameer

Engineering and Technology Journal, 2016, Volume 34, Issue 7, Pages 1457-1472

This research presents microstructural characterization of the CoNi Al shape memory alloy with focus on understanding the significant properties as well as the relation between the physical properties and microstructure of this alloy. Melting technique were used to prepare Co Al Ni shape memory alloys, where scanning electron microscope, light optical microscopy and x-ray diffraction investigations showed that structure of this alloy is polycrystalline double phase (β and γ) structure, and it found that the grain size and phase fraction of β phase was ranged from 9 to 16 μm and (50-80) % respectively. It was found that by increasing the heat treatment time the phase fraction of hard β phase increased and phase fraction of ductile γ phase decreased, and consequently the grain size and the hardness of β phase increased. Differential Scanning Calorimeter results showed that transformation temperature decreased by increasing Al/Co, that Co content affected on transformation temperature. Tafel Curves showed the corrosion behavior in simulation body fluid, where the corrosion rate was ranged from 0.13 to 0.47 mpy and increased with each of increasing the annealing time and Co content, and from cyclic curves, the pitting corrosion possibility is not observed due to the formation of a protective layerthat formed by Al element.According to these properties and behavior, it was found that this alloy could be a good choice to be used for biomedical applications, especially in surgical, catheter tools and medical instruments.