Utjecaj sadržaja nikla na svojstva Cu-Al-Mn-Ni legure s prisjetljivosti oblika

master's thesis

• Title (english): The effect of nickel content on properties of Cu-Al-Mn-Ni shape memory alloy
• Author: Ivana Krtić
• Mentor: Stjepan Kožuh (mentor)
• Committee member: Mirko Gojić (predsjednik povjerenstva)
• Committee member: Stjepan Kožuh (član povjerenstva)
• Committee member: Tamara Holjevac Grgurić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Metallurgy; Sisak
• Defense date and country: 2018-09-24, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Metallurgy

Abstract

U okviru ovog rada provedena je analiza utjecaja različitog sadržaja nikla (2-5 mas.%) na
mikrostrukturu i mikrotvrdoću Cu-Al-Mn-Ni legure s prisjetljivosti oblika. Pomoću peći za
taljenje obavljeno je taljenje i lijevanje ingota u vodom hlađenoj, posebno konstruiranoj
bakrenoj anodi koja je služila i kao kalup za lijevanje. Nakon taljenja uzorci su tri puta
pretaljivani upotrebom električnog luka kako bi se postigla homogenost kemijskog sastava.
Postupkom taljenja i lijevanja proizvedeni su uzorci valjkastog oblika odnosno ingoti
promjera 8 mm i duljine 15 mm. Odabrani uzorci su i toplinski obrađeni (900 °C/15min/H2O)
kako bi se pratio utjecaj toplinske obrade. Uzorci su analizirani u lijevanom i kaljenom stanju.
Mikrostrukturna analiza provedena je pomoću optičke i pretražne elektronske mikroskopije,
energetsko disperzijske spektroskopije i diferencijalno skenirajuće kalorimetrije. Ispitivanje
mikrotvrdoće provedeno je metodom po Vickersu. U svim analiziranim uzorcima utvrđena je
prisutnost β´1 martenzita. Porast sadržaja nikla do 3% utjecao je na smanjenje temperatura
faznih transformacija, dok je daljnjim porastom do 5% nikla uočen ponovni porast
temperatura faznih transformacija. Sličan trend zamijećen je i u vrijednostima mikrotvrdoće.

Abstract (english)

In this work, the effect of various nickel content (2-5 wt.%) on microstructure and
microhardness of Cu-Al-Mn-Ni shape memory alloy was analyzed. The melting furnace was
used to melt and cast the ingots in a water-cooled, specially designed copper anode which also
was used as a casting mould. After melting, the samples were remelted three times using an
electrical arc to achieve homogeneity of the chemical composition. By these procedures,
samples of cylindrical shape, ingots of 8 mm diameter and 15 mm length, were produced.
Selected samples were heat treated (900 °C/15min/H2O) to monitor the influence of heat
treatment. Samples were analyzed in as-cast and as-quenched state. Microstructural analysis
was performed by optical and scanning electron microscopy, energy dispersive spectroscopy
and differential scanning calorimetry. Microhardness testing was carried out by Vickers
method. In all analyzed samples, the presence of β'1 martensite was determined. The increase
of the nickel content up to 3% affected to the reduction of the phase transformations
temperatures, while a further increase of nickel content up to 5%, the phase transformations
temperatures rise again. A similar trend was observed in the values of microhardness.

• Keywords: Cu-Al-Mn-Ni legura; legure s prisjetljivosti oblika; martenzit; mikrostruktura; mikrotvrdoća
• Keywords (english): Cu-Al-Mn-Ni alloy; shape memory alloys; martensite; microstructure; microhardness
• Language: croatian
• URN:NBN: urn:nbn:hr:115:542592
• Project: Number: IP-2014-09-3405; Title: Dizajniranje mikrostrukture i funkcionalnih svojstava legura s prisjetljivosti oblika na bazi bakra; Acronym: DMFP-CuSMA; Leader: Mirko Gojić; Jurisdiction: Croatia; Funder: HRZZ; Funding stream: IP
• Study programme: Title: Graduate study program Metallurgy; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka metalurgije (magistar/magistra inženjer/inženjerka metalurgije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Public note: Ovaj rad je financirala Hrvatska zaklada za znanost projektom IP-2014-09-3405.
• Created on: 2018-09-28 07:55:08