Deformation Mechanisms and Evolution of Second Phase Particles of Mg–Y–Nd–Gd–Zr Alloy During Plane Strain Compression

Author(s):  
S. M. Fatemi ◽  
Y. Moradipour ◽  
M. Hajian
2015 ◽  
Vol 231 ◽  
pp. 1-10
Author(s):  
Magdalena M. Miszczyk ◽  
Henryk Paul

Early stages of recrystallization were observed for the Al-Mn-Mg-Zr(Sc) aluminium alloy containing a fine second phase particles. The samples were plane strain compressed to 40%, 60% and 83% and then annealed. The processes of the recovery and the nucleation of new grains were analysed with the use of scanning electron microscopy equipped with a high resolution electron backscattered diffraction facility. The deformed alloy contained a structure of flat grains situated parallel to the compression plane. After annealing, the structure coarsened. However, the growth of the new grains was strongly hindered by the presence of particles, and the elongated shape of the deformed grains was conserved up to the later stages of recrystallization. In the case ofthe samples deformed up to 40%, the structure was transformed by the mechanism of continuous recrystallization, whereas, in the case of the samples deformed up to 60% or 83%, both mechanisms- of continuous and discontinuous recrystallization - were valid. A particular role in the rise of thenuclei and the structure spheroidization is attributed to the thermally activated migration of the low-angle grain boundaries and the movement of the dislocations stored inside the cells. This leads to an increase of the misorientation angles across the pre-existing low-angle boundaries.


2014 ◽  
Vol 685 ◽  
pp. 27-30
Author(s):  
Yan Liu ◽  
Kai Wang ◽  
Yang Liu ◽  
Jian Ming Wang

A new technology to obtain a fine-structured and high-toughness HAZ of HSLA steel for high heat input welding is developed using metallurgical thermodynamics, physical chemistry of metallurgy and material processing methods synthetically in this study. A kind of HSLA steel is designed in this experiment. The thermal stability second phase particles which would not be dissolved or aggregated at high temperature will be expected by means of adding calcium and magnesium into the steel in the form of Si-Ca alloy and Mg-Zr alloy, respectively. The effect of calcium and magnesium addition on the morphology and distribution of the inclusions in the cast microstructure of HSLA steel was analysed. The results show that the distribution of the inclusions is more dense and uniform with respect to the raw steel, and the size of the inclusions is smaller than the ones in the raw steel after adding Ca and Mg elements. Ca and Mg elements can accelerate the nucleation of the inclusions. The nucleation rate of the Mg element is relatively higher. The number of the inclusions in the adding Mg steel decrease more slowly relative to the adding Ca steel with the extension of the steelmaking time.


2018 ◽  
Vol 8 (1) ◽  
pp. 110-114 ◽  
Author(s):  
I. A. Faizov ◽  
R. R. Mulyukov ◽  
D. A. Aksenov ◽  
S. N. Faizova ◽  
N. V. Zemlyakova ◽  
...  

Author(s):  
Angus Porter ◽  
Louise Makin ◽  
Brian Ralph

Much of the hardening of high strength aluminium alloys containing zirconium results from the precipitation of the metastable γ' (Al3Zr) phase (Ll2 structure, cube/cube related to the matrix). There exists some controversy in the literature as to the magnitude of the matrix (γ)-γ' misfit in Al-Zr alloys; the values reported range from 1% down to rather less than half this figure. In the present paper, the use of moire fringe imaging to study mismatch and misorientation between the γ and γ' lattice in a binary Al-Zr alloy will be considered. The advantages of this technique for the study of small second-phase particles are three-fold. The information obtained is specific to a single particle; the exact nature of the particle/matrix interface is unimportant, as long as the two lattices exhibit nearly coincident diffraction maxima; and mismatch and misorientation of particular sets of lattice planes can be determined from a single image.


2013 ◽  
Vol 578 ◽  
pp. 362-369 ◽  
Author(s):  
Lei Zhang ◽  
Chun-Guo Liu ◽  
Hui-Yuan Wang ◽  
Xiao-Long Nan ◽  
Zhi-Qiang Wu ◽  
...  

2012 ◽  
Vol 79 (3) ◽  
Author(s):  
Alan Needleman ◽  
Viggo Tvergaard ◽  
Elisabeth Bouchaud

Experimental observations have shown that the roughness of fracture surfaces exhibit certain characteristic scaling properties. Here, calculations are carried out to explore the extent to which a ductile damage/fracture constitutive relation can be used to model fracture surface roughness scaling. Ductile crack growth in a thin strip under mode I, overall plane strain, small scale yielding conditions is analyzed. Although overall plane strain loading conditions are prescribed, full 3D analyses are carried out to permit modeling of the three dimensional material microstructure and of the resulting three dimensional stress and deformation states that develop in the fracture process region. An elastic-viscoplastic constitutive relation for a progressively cavitating plastic solid is used to model the material. Two populations of second phase particles are represented: large inclusions with low strength, which result in large voids near the crack tip at an early stage, and small second phase particles, which require large strains before cavities nucleate. The larger inclusions are represented discretely and various three dimensional distributions of the larger particles are considered. The scaling properties of the predicted thickness average fracture surfaces are calculated and the results are discussed in light of experimental observations.


2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Hamad F. Alharbi ◽  
Monis Luqman ◽  
Ehab El-Danaf ◽  
Nabeel H. Alharthi

The deformation behavior and texture evolution of pure magnesium were investigated during plane strain compression, simple compression, and uniaxial tension at room temperature. The distinctive stages in the measured anisotropic stress-strain responses and numerically computed strain-hardening rates were correlated with texture and deformation mechanisms. More specifically, in plane strain compression and simple compression, the onset of tensile twins and the accompanying texture-hardening effect were associated with the initial high strain-hardening rates observed in specimens loaded in directions perpendicular to the crystallographic c-axis in most of the grains. The subsequent drop in strain-hardening rates in these samples was correlated with the exhaustion of tensile twins and the activation of pyramidal <c+a> slip systems. The falling strain-hardening rates were observed in simple compression and plane strain compression with loading directions parallel to the c-axis where the second pyramidal <c+a> slip systems were the only slip families that can accommodate deformation. For uniaxial tension with the basal plane parallel to the tensile axis, the prismatic <a> and second pyramidal <c+a> slips are the main deformation mechanisms. The predicted relative slip and twin activities from the crystal plasticity simulations clearly showed the effect of texture on the type of activated deformation mechanisms.


2013 ◽  
Vol 785-786 ◽  
pp. 76-80
Author(s):  
Hui Chao Cheng ◽  
Jing Lian Fan ◽  
Zhao Qian ◽  
Jia Min Tian

The present study describes the effect of trace ZrC additive on the microstructure and properties of Mo-Ti-Zr alloy fabricated by powder metallurgy method. The results indicate that, ZrC addition effectively enhanced the tensile strength of the alloy both at room-temperature and high-temperature, the alloy with 0.4wt% ZrC has the highest tensile strength, which is 611MPa and 513MPa at 25°C and 800°C, respectively. The tensile fracture mainly consists of intergranular rupture at room temperature, while dimple fracture occurred at high temperature, which indicating higher elongation. Through observation from the micrograph and EDS analysis, ZrxOyCz second-phase particles were observed,which is derived from part of ZrC particles reacted with the oxygen and can suppress the oxygen segregation on grain boundary.


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