Microstructure and Mechanical Properties of Ultrafine-Grained Magnesium AZ91 Alloy

2014 ◽  
Vol 782 ◽  
pp. 384-389 ◽  
Author(s):  
Stanislava Fintová ◽  
Libor Pantělejev ◽  
Ludvík Kunz

Microstructure, mechanical properties, cyclic plastic deformation behavior and fatigue strength of ultrafine-grained (UFG) magnesium alloy AZ91 processed by equal channel angular pressing (ECAP) were investigated. ECAP of originally cast alloy results in development of bimodal structure, improved yield stress, tensile strength and ductility when compared to the as-cast state. Endurance limit based on 107cycles is also improved, however exhibits large scatter. Initiation of fatigue cracks takes place in regions of large grains in the bimodal structure, where the content of Mg17Al12particles is low.

2013 ◽  
Vol 592-593 ◽  
pp. 805-808 ◽  
Author(s):  
Barbara Romelczyk ◽  
Tomasz Brynk ◽  
Rafal M. Molak ◽  
Anna Jastrzębska ◽  
Katarzyna Nowak ◽  
...  

Miniaturized Disc-Bend Test (MDBT), also called the Small Punch Test (SPT) is used for characterizing the mechanical properties of metals, when only a small volume of material is available. This study was dedicated to investigating the mechanical properties of AZ91 magnesium cast alloy. The casts were prepared via gravity sand casting and have sections with different wall thickness. The examined samples were cut out of 30 mm and 10 mm thick walls. The correlation between results obtained from the tensile tests and MDBT was determined.


2006 ◽  
Vol 503-504 ◽  
pp. 31-36 ◽  
Author(s):  
Johannes Mueller ◽  
Karsten Durst ◽  
Dorothea Amberger ◽  
Matthias Göken

The mechanical properties of ultrafine-grained metals processed by equal channel angular pressing is investigated by nanoindentations in comparison with measurements on nanocrystalline nickel with a grain size between 20 and 400 nm produced by pulsed electrodeposition. Besides hardness and Young’s modulus measurements, the nanoindentation method allows also controlled experiments on the strain rate sensitivity, which are discussed in detail in this paper. Nanoindentation measurements can be performed at indentation strain rates between 10-3 s-1 and 0.1 s-1. Nanocrystalline and ultrafine-grained fcc metals as Al and Ni show a significant strain rate sensitivity at room temperature in comparison with conventional grain sized materials. In ultrafine-grained bcc Fe the strain rate sensitivity does not change significantly after severe plastic deformation. Inelastic effects are found during repeated unloading-loading experiments in nanoindentations.


2008 ◽  
Vol 43 (23-24) ◽  
pp. 7409-7417 ◽  
Author(s):  
Matthias Hockauf ◽  
Lothar W. Meyer ◽  
Daniela Nickel ◽  
Gert Alisch ◽  
Thomas Lampke ◽  
...  

2003 ◽  
Vol 791 ◽  
Author(s):  
Yuri Estrin ◽  
Hyoung Seop Kim ◽  
Mark Bush

ABSTRACTPhase mixture models describing the mechanical properties of submicrometer grained metals are presented. In this approach, grain boundaries or cell walls are treated as a separate phase. Two cases are considered: the mechanical response of an ultrafine grained material and the process of grain refinement by equal channel angular pressing. Model predictions with regard to the evolution of the microstructure, strength and texture are verified for Cu.


Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1678 ◽  
Author(s):  
Chun Chiu ◽  
Hong-Min Huang

Mg97Zn1Y2 (at %) alloy with a long period stacking ordered (LPSO) phase has attracted a great deal of attention due to its excellent mechanical properties. It has been reported that this alloy could be fabricated by warm extrusion of rapid solidified alloy powders. In this study, an alternative route combining mechanical milling and equal channel angular pressing (ECAP) was selected to produce the bulk Mg97Zn1Y2 alloy. Microstructural characterization, mechanical properties and corrosion behavior of the ECAP-compacted alloys were studied. The as-cast alloy contained α-Mg and LPSO-Mg12Zn1Y1 phase. In the as-milled powder, the LPSO phase decomposed and formed Mg24Y5 phase. The ECAP-compacted alloy had identical phases to those of the as-milled sample. The compacted alloy exhibited a hardness of 120 HV and a compressive yield strength of 308 MPa, which were higher than those of the as-cast counterpart. The compacted alloy had better corrosion resistance, which was attributed to the reduced volume fraction of the secondary phase resulting in lower microgalvanic corrosion in the compacted alloy. The increase in Y content in the α-Mg matrix also contributed to the improvement of corrosion resistance.


2017 ◽  
Vol 743 ◽  
pp. 203-206 ◽  
Author(s):  
Alexander A. Kozulin ◽  
Vladimir A. Krasnoveikin ◽  
Vladimir A. Skripnyak ◽  
Evgeny N. Moskvichev ◽  
Valery E. Rubtsov

This study examines the effect of severe plastic deformation on the physical and mechanical properties of a light structural Al-Mg alloy. Severe plastic deformation has been performed by equal channel angular pressing through a die with an angle of 90° between the channels to produce ultrafine-grained structure in specimens of studied alloy. A complex investigation of the physical and mechanical properties of the processed alloy has been carried out to examine the microstructure and texture, and to measure microhardness, yield stress and ultimate tensile strength. The obtained results demonstrate high efficiency of the chosen treatment method and mode of producing a light ultrafine-grained alloy.


2008 ◽  
Vol 589 ◽  
pp. 111-116 ◽  
Author(s):  
György Krállics ◽  
Arpad Fodor ◽  
Jenő Gubicza ◽  
Z. Fogarassy

An Al-6082 alloy was subjected to equal channel angular pressing (ECAP) and subsequently to conventional forming methods such as shape rolling and rotary forging. The effect of different deformation techniques on the microstructure and the mechanical properties was studied. It was found that the shape rolling and rotary forging increased further the strength of ECAP-processed samples and induced a loss of ductility.


2005 ◽  
Vol 20 (2) ◽  
pp. 288-291 ◽  
Author(s):  
Y.H. Zhao ◽  
X.Z. Liao ◽  
Y.T. Zhu ◽  
R.Z. Valiev

Highest strength for 7075 Al alloy was obtained by combining the equal-channel-angular pressing (ECAP) and natural aging processes. The tensile yield strength and ultimate strength of the ECAP processed and naturally aged sample were 103% and 35% higher, respectively, than those of the coarse-grained 7075 Al alloy counterpart. The enhanced strength resulted from high densities of Guinier–Preston (G-P) zones and dislocations. This study shows that severe plastic deformation has the potential to significantly enhance the mechanical properties of precipitate hardening 7000 series Al alloys.


2014 ◽  
Vol 891-892 ◽  
pp. 1099-1104 ◽  
Author(s):  
Mandana Arzaghi ◽  
Christine Sarrazin-Baudoux ◽  
Jean Petit

The propagation of long fatigue cracks in ultra fine-grained (UFG) copper obtained by equal channel angular pressing (ECAP) is investigated in the mid ΔK range and in the near threshold regime. The crack growth rates in UFG copper are substantially faster than in coarse-grained (CG) copper. A huge influence of environment is observed, with growth rates faster of more than two orders of magnitude in air compared to vacuum. The crack growth mechanisms are discussed on the basis of microfractographic observations and the deformation texture.


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