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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.

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Crystallographic Texture and Grain Refinement in the CuCr Alloy Deformed by SPD Method

Urbańczyk-Gucwa A., Brzezińska A., Adamczyk-Cieślak B., Rodak K.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 4

1563--1568

EN

Microstructure and texture of the CuCr0.6 alloy processed by rolling with cyclic movement of rolls (RCMR) at room temperature were investigated. The RCMR processing was applied for the samples in different initial conditions in the solid solution followed by quenching into iced water at 1000°C for 3 h and in aging treatment conditions performed at 500°C for 2 h and at 700°C for 24 h. Application of the solution and aging processes prior to RCMR deformation results in the partial dissolution of Cr particles into the Cu matrix and precipitation of the second phase particles. RCMR processing with value of the total effective strain (εft) of 5 was introduced to the material. It was found that the RCMR method is effective in texture weakening. The obtained results revealed that there is a large similarity in texture orientations after RCMR processing independently of heat treatment conditions. Cyclic character of deformation leads to an incomplete transition of LAB to HAB.

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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.

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Microstructure and properties of CuCr0.6 and CuFe2 alloys after rolling with the cyclic movement of rolls

Rodak K., Urbańczyk-Gucwa A., Jabłońska M. B.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 2

500--507

EN

This work is focused on the effect of rolling with cyclic movement of rolls (RCMR) on microstructure, mechanical properties and electrical conductivity of CuCr0.6 and CuFe2 alloys in states after applying different heat treatments. The mechanical properties were determined by using MST QTest/10 machine equipped with digital image correlation (DIC). Scanning transmission electron microscopy (STEM) was used for microstructural characterization. The RCMR processed alloys shows high mechanical strength (UTS:539 MPa for CuCr0.6 alloy and UTS:393 MPa for CuFe2 alloy) attributed to the high density of coherent precipitates (after aging at 500 °C/2 h) and ultrafine grained structure. Plastically properties as uniform elongation (Agt) was about (∼1%) for both alloys after RCMR deformation. The RCMR processing induces a significant reduction of the electrical conductivity for samples, which were quenched before deformation, but for samples which were subjected to aging before deformation, the electrical conductivity was restored thanks to precipitation process.

5

Influence of heat treatment on the formation of ultrafine-grained structure of Al–Li alloys processed by SPD

Rodak K., Urbańczyk-Gucwa A., Jabłońska M., Pawlicki J., Mizera J.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 1

331--337

EN

In this study, binary Al–2.3wt%Li alloy, ternary Al–2.2wt%Li–0.1wt%Zr alloy and quaternary Al–2.2wt%Li–0.1wt%Zr–1.2wt%Cu alloy in the solution treated condition and additionally in aging condition were severely plastically deformed by rolling with cyclic movement of rolls (RCMR) method to produce ultrafine grained structure. Scanning transmission electron microscopy (STEM), scanning electron microscopy with EBSD detector (SEM/EBSD) were used for microstructural characterization and hardness test for a preliminary assessment of mechanical properties. The results shows, that the combination of aging treatments with RCMR deformation can effectively increase the hardness of Al–Li alloys. Second particles hinders the annihilation of dislocations in Al matrix during deformation leading to an increase of dislocation density. Significant amount of nanometric second particles in refined structure to ultrafine scale especially in Al–2.2wt%Li–0.1wt%Zr–1.2wt%Cu alloy effectively prevents the formation of high angle boundaries.

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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.

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Ultradrobnoziarnista mikrostruktura stopu CuFe2 walcowanego z poosiowym ruchem walców

Urbańczyk-Gucwa A., Bednarczyk I., Płachta A., Sobota J., Głuchowski W., Rdzawski Z., Rodak K.

Inżynieria Materiałowa

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2015

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Vol. 36, nr 5

233--237

PL

W prezentowanej pracy przedstawiono wyniki badań mikrostruktury i twardości stopu CuFe2 po zastosowaniu intensywnego odkształcenia plastycznego SPD realizowanego za pomocą walcowania z poosiowym ruchem walców (RCMR). Przeprowadzone badania wykazały, iż tą metodą można uzyskać rozdrobnienie ziaren stopu CuFe2 do wielkości ultradrobnoziarnistej. Intensywność rozdrobnienia zależy od parametrów odkształcenia: amplitudy wychyleń walców A, częstotliwości ruchu poosiowego walców f, gniotu względnego całkowitego εh, prędkości walcowania v. Walcowanie z poosiowym ruchem walców realizowano przy stałych wartościach: v = 1 obr/min, f = 1 Hz. Maksymalna wartość gniotu względnego całkowitego po 6 przepustach wynosiła εh6 = 80%. Zmiennym parametrem była amplituda wychyleń walców wynosząca 0, 0,8 i 1,6 mm. Mikrostrukturę stopu CuFe2 analizowano za pomocą mikroskopu świetlnego (LM) oraz skaningowego transmisyjnego mikroskopu elektronowego (STEM). Walcowanie z poosiowym ruchem walców stopu CuFe2 w początkowym etapie odkształcenia (εh2 = 37%) powoduje niejednorodność odkształcenia (zróżnicowanie mikrostruktury na przekroju poprzecznym). Wzrost gniotu względnego (εh6 = 80%) przyczynia się do ujednorodnienia mikrostruktury. Dokonując pomiarów twardości na próbkach walcowanych konwencjonalnie oraz metodą RCMR przy różnej amplitudzie walcowania, stwierdzono, że wraz ze wzrostem amplitudy walcowania maleje twardość stopu. Amplituda poprzecznego przemieszczenia walców jest tym czynnikiem, który powoduje lokalną destabilizację mikrostruktury w wyniku nagłej zmiany drogi odkształcania. Może to powodować efekt mięknięcia materiału. Cykliczne odkształcanie powoduje intensywne formowanie granic dyslokacyjnych rozprzestrzeniających się w różnych kierunkach ze względu na aktywność licznych systemów poślizgu. W wyniku takiego odkształcania otrzymuje się ultradrobnoziarnistą mikrostrukturę.

EN

The results of microstructure and hardness investigations of the CuFe2 alloy after the application of severe plastic deformation (SPD) implemented by rolling with cyclic movement of rolls (RCMR) are presented in this paper. Performed substructure investigations showed that using the RCMR method can refine the microstructure of CuFe2 alloy to the ultrafine scale. The intensity of microstructure refinement depends on: the amplitude of rolls movement A, the frequency of rolls movement f, rolling reduction εh, the rolling rate v. The rolling with the cyclic movement of the rolls was carried out at constant values: v = 1 rpm, f = 1 Hz. Maximal values of rolling reduction at 6 passes was εh6 = 80%. Variable parameter was the amplitude of rolls movement 0, 0.8 and 1.6 mm. The microstructure of the CuFe2 alloy was analyzed using light microscope (LM) and scanning transmission electron microscope (STEM). In the initial stage of deformation (εh2 = 37%) by using rolling with cyclic movement of the rolls method, the structure is heterogeneous (in cross-section plane the microstructure is uniformly deformed). Increase of rolling reduction (εh6 = 80%) causes, that the structure is more homogeneous. Based on hardness measurement for sample conventionally rolled and samples deformed by using RCMR method with different value of amplitude of rolls movement, it was found, that with increase of amplitude of rolls movement the hardness of the alloy decrease. The amplitude of rolls movement is this parameter, which induces local destabilization in structure as a result of change in deformation path. This may cause the effect of strain softening in material. Cyclic deformation causes formation dislocation boundaries which propagate in different direction due to activity of a number of slip system. As a result of this deformation is obtained ultrafine grain microstructure.