Corrosion behavior of Shape Memory Alloy in NaCl environment and recovery maintenance in Cu-Zn-Al sysytem

Abstract

Shape memory effect (SME) and the relation with corrosion behavior of Cu-Zn-Al Smart Memory Alloys (SMAs) were investigated using different techniques: Scanning Electron Microscopy equipped with an Energy Dispersive System, X-Ray Diffraction analysis, Electrochemical Test in NaCl solutions with different concentrations (0.035%, 0.35% and 3.5%), which simulate coastal conditions, mechanical characterization through tensile test and guided bend test. SMAs are an important class of smart materials able to recover after deformation a pre-imposed shape through a temperature modification. These alloys show great potential, finding several applications in medicine and in different types of industry sectors (aerospace, architecture, automotive etc.). Cu-based SMAs, including Cu-Zn-Al alloys, have lower production costs with respect to Ni-Ti alloys as well as good possibility in seismic and architectural applications. A Cu-Zn-Al alloy with a theoretical composition of 25 wt.% Zn and 4 wt.% Al was produced by casting method. The aim of this study is to characterize the microstructure, the mechanical properties and the corrosion behavior through different kind of standard corrosion tests of this alloy and to evaluate the effect of corrosion damage on the shape memory recovery capability through a combination of corrosion and thermos-mechanical cyclic test and SEM observation

Corrosion Behavior of the Cu24Zn5Al Alloy in Sodium Sulfate Solution in the Presence of 1-Phenyl-5-mercaptotetrazole

“…This confirms the assertion that a Cu2O film was formed on the surface of the copper alloy in a neutral medium [41], which has a similar role as the film formed during immersion in the Based on the results presented in Table 3, it can be concluded that the presence of chloride ions at concentrations of 1 × 10 −4 mol/dm 3 , 1 × 10 −3 mol/dm 3 , and 1 × 10 −2 mol/dm 3 has an inhibitory effect, as the corrosion current obtained in these solutions is lower than that obtained in the 0.1 mol/dm 3 sodium sulfate solution, while the concentration of chloride ions of 5 × 10 −2 mol/dm 3 has a significant influence on increasing the corrosion current of the Cu24Zn5Al alloy. The inhibitory effect of the present chloride ions has been confirmed by other authors as well [35,56,57].…”

“…The main anodic reaction of Cu24Zn5Al alloy in 0.1 mol/dm 3 Na 2 SO 4 containing chloride ions can be represented by the following equations [1,38,[51][52][53][54][55][56]:…”