Changes in the properties of Cu-Al-Mn shape memory alloy due to quaternary addition of different elements

Abstract

Advantages of Cu based shape memory alloy include amongst other features, high transformation temperature, low cost of production, ease in manufacturing processes and ability to vary the achieved properties through alloying additions. It has been often reported that these alloys are very sensitive to the alloying additions in terms of properties achieved and phase precipitation necessary for development of shape memory properties. This behaviour in Cu based shape memory alloys i.e. being very sensitive to its constituents can be used positively to design alloys with pre set properties if the alloying additions and their percentages are properly controlled.In an attempt to understand the effect of different alloying additions, 2% of different elements [Zn, Si, Mg & Cr] were added to a known Cu-based shape memory alloy [Cu-12.5 wt% of Al-5 wt % of Mn]. The objective was to ascertain changes or improvements achieved due to the additions in terms of microstructural changes, hardness, phase precipitation and transformation temperatures. Attempts have been made to analyze the changes in properties achieved in the base Cu-Al-Mn alloys due to the quaternary additions. Grain structure with α+β phases, which is a pre requisite for martensite formation on quenching is seen in all the alloys indicating that all the alloys have potential to exhibit the shape memory behaviour. The martensite formation with different morphologies is observed in the quenched samples however. XRD results have identified the precipitated phases to be the martensitic phases. The DSC results indicate clear transformation peaks in most of the samples with significantly high transformation temperatures. The findings confirm the variation in properties achieved due to different additions and improvements achieved in terms of higher transformation temperatures and martensite formation due to the alloying additions. An attempt has been made to understand the findings.

Improving the thermomechanical and magnetic properties of CuMnAl Heusler alloy by TiB doping

“…4a. Cu-based polycrystalline memory alloys with a high grain sizes are, generally, fragile and tend to cause intergranular fractures due to the high degree of order in the austenite phase with structure B2, DO 3 , or L2 1 and the extremely high elastic anisotropy rate of the bphase [17]. Figure 4d shows a representative SEM image for the CuAlMn sample.…”

“…Among the systems that behave like FSMA, the CuAlMn alloys present advantages that include high transformation temperature, low production cost, ease of manufacturing processes, and the ability to vary the properties achieved through modifications to the alloy and processing [17]. The CuAlMn system alloys present a high-temperature b-phase, with the bcc A2 structure that undergoes an order-disorder transition of two stages: A2 (disordered Cu bcc) -B2 (CuAl) -DO 3 (Cu 3 Al), with the order DO 3 -L2 1 representing an intermediate stage between DO 3 (Cu 3 Al) and L2 1 (Cu2MnAl) [18].…”

Quaternary Element Incorporation Effects on Thermal Properties and Crystal-Micro Structure of Cu-Al-Fe High Temperature Shape Memory Alloys

“…Among the quaternary Cu-based shape memory alloys mostly investigated, the Cu-Al-Ni, Cu-Al-Zn, and Cu-Al-Mn alloys have been studied extensively [9]. In the literature, there are studies about adding Ni, Mn, Be to CuAl shape memory alloy.…”

Nonlinear analysis of shape memory alloy beam under the thermal and the mechanical loads

“…The relationship between stress and strain is nonlinear in the process of phase transformation, which made SMA possess superelastic effect. And the shape memory effect can make the material recover its pristine shape after a residual strain by heating the material [7][8][9][10].…”