Microstructure and Hardness of Copper Based Shape Memory Alloys with Fourth Alloying Elements
Keywords:Shape memory alloys, Cu based shape memory alloys, fourth alloying elements, microstructure, hardness
AbstractMany potential applications of Cu based shape memory alloys (SMAs) are restricted due to the brittleness of the material. This research was conducted to enhance the mechanical properties of the Cu based SMAs. The research examined the effects of adding the fourth alloying elements, i.e., Boron (B), Cobalt (Co) and Titanium (Ti) on the microstructures and mechanical properties of the Cu based SMAs. The fabrication of Cu-Al-Ni alloys with these fourth alloying elements was carried out using a casting method. Several characterization tests were conducted to identify the effects of the fourth alloying elements using Scanning Electron Microscope (SEM), Optical Microscope, and Vickers hardness test. From the microstructural observation, it was found that the grain sizes of these alloys were refined with the addition of the fourth alloying elements. The addition of B shows the most fined grain size. The SEM results indicate that the microstructures consisted of two types of martensite, which were ð›½1with an 18R structure, and ð›¾1 with a 2H structure. The ð›¾1, looking like parallel martensite morphologies, are known as lamella structures. This type of lamella morphologies has also grown into grain. The ð›½1 phase is typically formed with self accommodating groups in two different morphologies, plates and needles. The precipitation existed in the structure known as ð›¾2, which also existed and acted like barriers in the grain boundaries. ð›¾2 precipitates can be found in grain boundaries and in between structure ð›½1 and ð›¾1. The addition of the fourth alloying elements shows an increment in the hardness of the alloys in which the addition of Ti element demonstrates the highest hardness value.
Otsuka K. and Wayman C.M., 1999. Shape Memory Materials, New York, Cambridge University Press.
Tadaki T., 2002. Cu Based Shape Memory Alloys, Shape Memory Materials, Cambridge: Cambridge University Press.
Lojen G., GojiÄ‡ M. and AnÅ¾el I., 2013. Continuously Cast Cuâ€“Alâ€“Ni Shape Memory Alloy â€“ Properties in As-cast Condition, Journal of Alloys and Compounds, 580: p. 497-505.
Miyazaki S., Kawai T. and Otsuka K., 1982. On The Origin of Intergranular Fracture in Î² Phase Shape Memory Alloys, Scripta Metallurgica, 16(4): 431-436.
Saud S.N., Hamzah E., Abu Bakar T.A., Hosseinian S.R., 2013. A Review on Influence of Alloying Elements on the Microstructure and Mechanical Properties of Cu-Al-Ni, Jurnal Teknologi, 64: 51-56.
Morris M.A., 1991. Influence of Boron Additions on Ductility and Microstructure of Shape Memory Cu-Al-Ni Alloys, Scripta Metallurgica et Materialia, 25(11): 2541-2546.
Hurtado, I., Ratchev P., Van Humbeeck J., Delaey L., 1996. A Fundamental Study of The Ï‡-phase Precipitation in Cu-Al-Ni-Ti-(Mn) Shape Memory Alloys, Acta Materialia, 44(8): 3299-3306.
SarÄ± U. and Aksoy Ä°., 2006. Electron Microscopy Study of 2H and 18R Martensites in Cuâ€“11.92 wt% Alâ€“3.78 wt% Ni Shape Memory Alloy, Journal of Alloys and Compounds, 417(1â€“2): 138-142.
Wee Y.C., Abubakar T., Hamzah E., Saud S., 2015. Phase Transformation and Microstructure Behaviour of Cu-Al-Ni Shape Memory Alloys Incorporated with Cobalt Addition, Jurnal Teknologi, 74: 53-56.
Sure G.N. and Brown L.C., 1985. The Fatigue Properties of Grain Refined Î²-Cu Al Ni Strain-Memory Alloys, Scripta Metallurgica, 19(4): 401-404.
How to Cite
Copyright of articles that appear in Jurnal Mekanikal belongs exclusively to Penerbit Universiti Teknologi Malaysia (Penerbit UTM Press). This copyright covers the rights to reproduce the article, including reprints, electronic reproductions or any other reproductions of similar nature.