Influence of heat treatment on the corrosion properties of CuAlMn shape memory alloys

Abstract

This paper reports on the influence of heat treatment on the corrosion properties of CuAlMn alloy in 0.1%, 0.9% and 1.5% NaCl solution (pH = 7.4). Heat treatment of alloy samples was performed by samples annealing at 900°C for 30 min. Electrochemical methods of investigations included measuring the open circuit potential (Eoc) and linear and potentiodynamic polarisation. Optical microscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to study the morphology and composition of the corroded surfaces, along with X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Heat-treated samples have slightly more positive values of Eoc, slightly lower values of corrosion current density and higher values of polarisation resistance compared with the as-cast alloy. The microscopic analysis showed the rough surfaces due to corrosion processes. Increasing the electrolyte concentration leads to an increase in alloy surface damage. AFM and SEM examinations showed that the surface was covered with interlaced layers of corrosion products, as well as cracks and ducts formed by their dissolution. EDX and XPS analyses showed that corrosive products consist mainly of aluminium and manganese oxides and chlorides. Annealed CuAlMn alloy samples have significantly lower copper content compared with the as-cast CuAlMn alloy.

Wear and corrosion behavior of selected up-quenched and step-quenched CuZnSn shape memory alloys

“…It is observed that the current density of the step-quenched A 7b are dissimilar to those of A alloys in terms of their polarization behavior. The pseudo-passive zone, which follows the Tafel region of the anodic branches of polarization curves, is where the anodic current densities show a slight decrease due to the formation of soluble corrosion products on the surface of the samples [45]. In corrosion studies of Cu-Al-Mn SMAs by Vrsalović et al, [45] and Cu-Zn-Ni SMAs by [34], similar anodic behavior has been observed.…”

“…The pseudo-passive zone, which follows the Tafel region of the anodic branches of polarization curves, is where the anodic current densities show a slight decrease due to the formation of soluble corrosion products on the surface of the samples [45]. In corrosion studies of Cu-Al-Mn SMAs by Vrsalović et al, [45] and Cu-Zn-Ni SMAs by [34], similar anodic behavior has been observed. There is a marginal difference in corrosion density for the up-quenched (4.18 mA/cm 2 ) and directquenched (3.98 mA/cm 2 ) samples while the step-quenched samples had the least corrosion density (3.04 mA/cm 2 ).…”

“…The Platinum electrode was used as the counter electrode for the corrosion cell. The surface of each corrosion test sample was ground using silicon carbide abrasive papers of 220, 800, 1000, 1200, and 2000 grits, polished with Al 2 O 3 powder suspension, washed in ethanol solution, and dried [45]. The prepared surfaces of mounted samples were immersed in the corrosion cell which contains the corrosive solutions.…”

Razvoj legura s prisjetljivošću oblika na bazi bakra u okviru znanstveno-istraživačkih projekata na Metalurškom fakultetu Sveučilišta u Zagrebu

“…Analize EDS i XPS (rendgenska fotoelektronska spektroskopija) pokazale su da se korozivni proizvodi sastoje uglavnom od aluminijevih i manganovih oksida i klorida. 68 Ispitivanje korozijskog ponašanja legure Cu- Korozijsko ponašanje legure Cu-11Al-3,4Mn-3,2Zn u 0,5 mol dm −3 otopini Na 2 SO 4 pri različitim temperaturama elektrolita ispitano je različitim nedestruktivnim elektrokemijskim metodama, kao što su mjerenje potencijala otvorenog strujnog kruga, metoda linearne polarizacije i elektrokemijske impedancijske spektroskopije kao i destruktivnim metodama u širokom području potencijala, kao što su potenciodinamička polarizacijska metoda i metoda cikličke polarizacije. 76 Rezultati ispitivanja pokazali su negativan utjecaj temperature elektrolita na korozijsku otpornost legure, što je vidljivo iz negativnosti vrijednosti E OC , opadanja vrijednosti polarizacijskog otpora, porasta vrijednosti gustoće korozijske struje kao i smanjivanja polumjera kapacitivnog polukruga kod impedancijskih mjerenja (slika 18).…”

Comparison of corrosion behaviour of copper and copper alloys in aqueous chloride solution

“…Cu-Al-Ni and Cu-Al-Mn SMAs have been extensively investigated and have found practical usage in actuator and sensor manufacturing, electronics, computers parts, automotive and aircraft industries, robotics, and civil engineering industry, etc. [9][10][11][12][13].…”