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Refinement of Al-5%Cu and Al-25%Cu Alloys by Means of KoBo Methods

Rodak K., Brzezińska A., Sobota J.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 4

1477--1482

EN

This study was undertaken to investigate the effect of severe plastic deformation (SPD) by extrusion combined with reversible torsion (KoBo) method on microstructure and mechanical properties of Al-5Cu and Al-25Cu alloys. The extrusion combined with reversible torsion was carried out using reduction coefficient of λ = 30 and λ = 98. In this work, the microstructure was characterized by light microscopy (LM), scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM). Compression test and tensile test were performed for deformed alloys. The binary Al-5Cu and Al-25Cu alloys consist of the face cantered cubic (FCC) α phase in the form of dendrites and tetragonal (C16) θ-Al2Cu intermetallic phase observed in interdentritic regions. The increase of Cu content leads to increase of interdentritic regions. The microstructure of the alloys is refined after applying KoB deformation with λ = 30 and λ = 98. Ultimate Tensile Strength (UTS) of Al-5Cu alloy after KoBo deformation with λ = 30 and λ = 98 reached about 200 MPa. UTS for samples of Al-25Cu with λ = 30 and λ = 98 increased compared to Al-5Cu alloy and exceed 320 MPa and 270 MPa respectively. All samples showed increase of plasticity with increase of reduction coefficient. Independently of reduction coefficient, the compressive strain of Al-5Cu alloys is about 60%. The Al-25Cu alloy with λ = 98 showed the value of compressive strain exceed 60%, although for this same alloy but with λ = 30, the compressive strain is only 35%.

2

Microstructural Features and Mechanical Properties after Applying Rolling with Cyclic Movement of Rolls of an Al-Li Alloys

Brzezińska A., Urbańczyk-Gucwa A., Molak R., Rodak K.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 4

1533--1540

EN

Two strength-age hardening aluminum-lithium alloys: Al-2.3wt%Li and Al-2.2wt%Li-0.1wt%Zr in two different heat treatment conditions: solution state (S) and additionally in aging state (A) were severely plastically deformed by rolling with cyclic movement of rolls (RCMR) method to produce ultrafine - grained structure. Two thermo-mechanical treatments were used: (S+A+RCMR) and (S+RCMR+A+RCMR). To investigate the combined effect of plastic deformation and heat treatment, tensile tests were performed. Microstructural observations were undertaken using scanning transmission electron microscopy (STEM), and scanning transmission electron microscopy (SEM) equipped with electron backscattering diffraction detector (EBSD). Based on the obtained results, it can be deduced that maximum mechanical properties as: yield strength (YS) and ultimate tensile strength (UTS) couldbe achieved when the microstructure of alloys is in (S+A+RCMR) state. For samples in (S+RCMR+A+RCMR) state, ductility is higher than for (S+A+RCMR) state. The microstructural results shows that the favourable conditions for decreasing grain size of alloys is (S+A+RCMR) state. Additionally, in this state is much greater dislocation density than for (S+RCMR+A+RCMR) state. The microstructure of alloys in (S+RCMR+A+RCMR) state is characterized by grains/subgrains with higher average diameter and with higher misorientation angles compared with (S+A+RCMR) state.

3

Influence of Solid Solution and Aging Treatment Conditions on the Formation of Ultrafine-Grained Structure of CuCr0.6 Alloy Processed by Compression with Oscillatory Torsion

Urbańczyk-Gucwa A., Brzezińska A., Rodak K.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 4

2061--2066

EN

The samples of the CuCr0.6 alloy in the solution treated and additionally in aging states were severely plastically deformed by compression with oscillatory torsion (COT) method to produce ultrafine – grained structure. The samples were processed by using process parameters as: frequency of torsion (f = 1.6 Hz), compression speed (v = 0.04 mm/s), angle torsion (α = ±6°), height reduction (Δh = 7 mm). The total effective strain was εft = 40. The microstructure has been analyzed by scanning transmission electron microscope (STEM) Hitachi HD-2300A equipped with a cold field emission gun at an accelerating voltage of 200 kV. The quantitative microstructure investigations as disorientation angles were performed using a FEI INSPECT F scanning electron microscope (SEM) equipped with a cold field emission gun and a electron backscattering diffraction (EBSD) detector. The mechanical properties were determined using MST QTest/10 machine equipped with digital image correlation (DIC). The COT processed alloy previously aged at 500°C per 2h shows high mechanical strength, ultimate tensile strength UTS: 521 MPa and yield tensile strength YS: 488 MP attributed to the high density of coherent precipitates and ultrafine grained structure.

4

Influence of Solution and Aging Treatment Conditions on the Formation of Ultrafine-Grained Structure of CuFe2 Alloy Processed by Rolling with Cyclic Movement of Rolls

Urbańczyk-Gucwa A., Radwański K., Rodak K.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2B

1235--1240

EN

The effect of second phase particles on grain refinement in CuFe2 alloy has been investigated by using rolling with the cyclic movement of rolls (RCMR) method. Two different population of second phase particles of Fe: coherent, about 10 nm in diameter and about 100 nm in size were obtained by applying aging treatment followed at 500°C for 2 h and at 700°C for 24 h respectively. In addition, solution treated samples were deformed by RCMR method at the same parameters. The microstructures of the CuFe2 alloy were analyzed using light microscope (LM), electron backscattered diffraction (EBSD) microscope technique and scanning transmission electron microscope (STEM). The presence of high-density of coherent Fe particles in the matrix inhibits recovery process and in the result obtained grain/subgrain boundaries have diffused character and are weakly visible. The largest particles which are not coherent with the matrix act as an effective barrier against the boundary motion.