Ivana Ivanić

Corrosion Protection of Copper in Sodium Chloride Solution using Propolis

In this investigation the possibility of inhibiting corrosion of copper using ethanol extract of propolis in 0.5 mol dm-3 NaCl solution was investigat

Microstructural characterization of Cu82.3Al8.3Mn9.4 shape memory alloy after rolling

In this paper, the microstructure of Cu82.3Al8.3Mn9.4 (in wt. %) shape memory alloy after hot and cold rolling was investigated. The Cu82.3Al8.3Mn9.4 alloy was produced by a vertical continuous casting method in the form a cylinder rod of 8 mm in diameter. After the casting, hot and cold rolling was performed. By hot rolling a strip with a thickness of 1.75 mm was obtained, while by cold rolling a strip with a thickness of 1.02 mm was produced. After the rolling process, heat treatment was performed. Heat treatment was carried out by solution annealing at 900 °C held for 30 minutes and water quenched immediately after heating. The microstructure characterization of the investigated alloy was carried out by optical microscopy (OM), scanning electron microscopy (SEM) equipped with a device for energy dispersive spectroscopy (EDS). Phase transformation temperatures and fusion enthalpies were determined by differential scanning calorimetry (DSC) method. The homogenous martensite microstructure was confirmed by OM and SEM micrographs after casting. During rolling the two-phase microstructure occurred. Results of DSC analysis showed martensite start (M s ), martensite finish (M f ), austenite start (A s ) and austenite finish (A f ) temperatures.

Shape Memory Alloys (Part I): Significant Properties

U ovom radu naveden je pregled termomehanickih svojstava slitina s prisjetljivosti oblika i opca obilježja martenzitne transformacije. Slitine s prisjetljivosti oblika pripadaju skupini relativno „novih“ metalnih materijala, te se od drugih slitina (npr. dentalnih slitina) razlikuju po pseudoelasticnosti i efektu prisjetljivosti oblika. Pseudoelasticnost je povezana s nastankom martenzita transformacijom austenita. Austenitno – martenzitna transformacija može se inducirati mehanickim (naprezanjem) ili toplinskim (zagrijavanje i hlađenje) metodama. Tijekom martenzitne transformacije ne odvijaju se procesi difuzije, nego dolazi do neelasticne deformacije kristalne resetke. Austenitno – martenzitnu transformaciju karakteriziraju temperature pocetka te zavrsetka austenitne i martenzitne transformacije (As i Af, Ms i Mf). Također su detaljno objasnjeni jednosmjerni, dvosmjerni i visestruki efekt prisjetljivosti oblika, te je uoceno da je jednosmjerni efekt prisjetljivosti oblika jos uvijek najcesce koristeni efekt.

Slitine s prisjetljivosti oblika (II. dio): podjela, proizvodnja i primjena

Slitine s prisjetljivosti oblika funkcionalni su “pametni” materijali s jedinstvenim svojstvom prisjetljivosti oblika. Prisjetljivost oblika karak