scholarly journals Hot-Extruded and Cold-Rolled Textures of the Matrix Aluminum in Deformation Processed Two-Phase Nb/Al Metal-Metal Composites

2003 ◽  
Vol 35 (3-4) ◽  
pp. 273-282 ◽  
Author(s):  
L. Q. Chen ◽  
N. Kanetake
Keyword(s):  
Cold Rolling ◽  
Hot Extrusion ◽  
Orientation Distribution ◽  
Rolling Process ◽  
Distribution Functions ◽  
Second Phase ◽  
Metal Composite ◽  
Two Phase ◽  
Metal Metal ◽  
The Matrix

In this article, the powder metallurgy technique combined with flat hot-extrusion and cold rolling processes was employed to fabricate 10 and 20vol.%Nb/Al metal–metal composite sheets. The hot-extruded and coldrolled textures of the matrix aluminum in these metal–metal composite sheets were investigated by three dimensional orientation distribution functions (ODFs) analysis. The results show that the extrusion mode and large second phase particulate metal, Nb, have strong influence on the development of the extrusion and cold rolling textures in composites’ matrix. The matrix Al forms β-fiber textures after flat hot extrusion, where the components consist of B′-{011} ‹322›, S′-{124} ‹654› and C′-{113}h332i. After cold rolling process, only B′-{011} ‹322› changed to B-{011} ‹211› while the other components remained the same. The large particles in composites affect the matrix deformation in such a way that separates the distorted or bound zones from the deformation zones, which resulted in the final cold rolling deformation textures.

scholarly journals MC2: a two-phase algorithm for leveraged matrix completion

2018 ◽  
Vol 7 (3) ◽  
pp. 581-604 ◽  
Author(s):  
Armin Eftekhari ◽  
Michael B Wakin ◽  
Rachel A Ward
Keyword(s):  
Broad Class ◽  
Matrix Completion ◽  
A Priori ◽  
Total Sample ◽  
Second Phase ◽  
Sample Complexity ◽  
Two Phase ◽  
The Matrix ◽  
Leverage Scores ◽  
Uniform Random Sampling

Abstract Leverage scores, loosely speaking, reflect the importance of the rows and columns of a matrix. Ideally, given the leverage scores of a rank-r matrix $M\in \mathbb{R}^{n\times n}$, that matrix can be reliably completed from just $O (rn\log ^{2}n )$ samples if the samples are chosen randomly from a non-uniform distribution induced by the leverage scores. In practice, however, the leverage scores are often unknown a priori. As such, the sample complexity in uniform matrix completion—using uniform random sampling—increases to $O(\eta (M)\cdot rn\log ^{2}n)$, where η(M) is the largest leverage score of M. In this paper, we propose a two-phase algorithm called MC2 for matrix completion: in the first phase, the leverage scores are estimated based on uniform random samples, and then in the second phase the matrix is resampled non-uniformly based on the estimated leverage scores and then completed. For well-conditioned matrices, the total sample complexity of MC2 is no worse than uniform matrix completion, and for certain classes of well-conditioned matrices—namely, reasonably coherent matrices whose leverage scores exhibit mild decay—MC2 requires substantially fewer samples. Numerical simulations suggest that the algorithm outperforms uniform matrix completion in a broad class of matrices and, in particular, is much less sensitive to the condition number than our theory currently requires.

scholarly journals Microstructural characterization of Cu82.3Al8.3Mn9.4 shape memory alloy after rolling

10.30544/314 ◽  
2017 ◽  
Vol 23 (3) ◽  
pp. 281-289
Author(s):  
Mirko Gojić ◽  
Stjepan Kožuh ◽  
Ivana Ivanić ◽  
Magdalena Selanec ◽  
Tamara Holjevac Grgurić ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Shape Memory Alloy ◽  
Cold Rolling ◽  
Shape Memory ◽  
Microstructural Characterization ◽  
Rolling Process ◽  
Scanning Calorimetry ◽  
Two Phase ◽  
Hot And Cold Rolling

In this paper, the microstructure of Cu82.3Al8.3Mn9.4 (in wt. %) shape memory alloy after hot and cold rolling was investigated. The Cu82.3Al8.3Mn9.4 alloy was produced by a vertical continuous casting method in the form a cylinder rod of 8 mm in diameter. After the casting, hot and cold rolling was performed. By hot rolling a strip with a thickness of 1.75 mm was obtained, while by cold rolling a strip with a thickness of 1.02 mm was produced. After the rolling process, heat treatment was performed. Heat treatment was carried out by solution annealing at 900 °C held for 30 minutes and water quenched immediately after heating. The microstructure characterization of the investigated alloy was carried out by optical microscopy (OM), scanning electron microscopy (SEM) equipped with a device for energy dispersive spectroscopy (EDS). Phase transformation temperatures and fusion enthalpies were determined by differential scanning calorimetry (DSC) method. The homogenous martensite microstructure was confirmed by OM and SEM micrographs after casting. During rolling the two-phase microstructure occurred. Results of DSC analysis showed martensite start (Ms), martensite finish (Mf), austenite start (As) and austenite finish (Af) temperatures.

Microstructure, Texture and Recrystallisation Mechanisms of an Al-20%Sn Deformation Processed Metal-Metal Composite

2012 ◽  
Vol 715-716 ◽  
pp. 522-527 ◽  
Author(s):  
Rafael Schouwenaars ◽  
Hugo A. Duran ◽  
Víctor H. Jacobo ◽  
Armando Ortiz
Keyword(s):  
Phase Distribution ◽  
Rolling Texture ◽  
Coarse Grained ◽  
Al Alloy ◽  
Second Phase ◽  
Metal Composite ◽  
Fine Grained ◽  
Texture Change ◽  
Metal Metal ◽  
Cold Rolled

Al-Sn alloys for tribological applications are industrially important alloys which have attracted little attention over their history. Being cold rolled directly from thin cast slabs and consisting of two ductile phases, their processing and physical behaviour are distinct from classical Al-Alloys. During cold rolling, the coarse-grained, random texture of the slab is transformed into the classical rolling texture of a fine-grained Al-alloy, with elongated Al-grains delimited by thin Sn-ribbons. During annealing at 300°C, the interior of the Al-grains recrystallises rapidly while the liquid Sn-phase migrates toward Al-grain triple lines to form a reticular structure. A weak texture, dominated by Goss and P is produced. Grain growth within the original cold-rolled grains is fast, but once the recrystallised grain size reaches the length scale of the second-phase distribution, it slows down and both phases coarsen simultaneously, accompanied by a significant texture change.

Analysis of Deformation Texture in AISI 304 Steel Sheets

2013 ◽  
Vol 203-204 ◽  
pp. 105-110 ◽  
Author(s):  
Agnieszka Kurc-Lisiecka ◽  
Wojciech Ozgowicz ◽  
Wiktoria Ratuszek ◽  
Joanna Kowalska
Keyword(s):  
Cold Rolling ◽  
Rolling Texture ◽  
Orientation Distribution ◽  
Deformation Texture ◽  
Distribution Functions ◽  
Rolled Strip ◽  
Aisi 304 ◽  
Aisi 304 Steel ◽  
Cold Rolled ◽  
Two Phases

The textures of cold-rolled AISI 304 austenitic steel were the object of the investigations. The austenite steel was deformed by cold-rolling to 20, 40 and 70% reduction. A significant amount of martensite, formed due to the strain induced (γ®a’) transformation, was detected in the deformed structure by applying magnetic and X-ray diffraction methods. Texture analysis was performed on the basis of the orientation distribution functions (ODFs) calculated from the experimental pole figures. The texture measurements of both phases were conducted from the center layers of the cold-rolled strip. In the case of metastable austenite AISI 304 steel the texture development was very complex because three processes were proceded simultaneously during the cold-rolling, namely: plastic deformation of the austenitic g-phase, strain induced phase transformation γ®a’ and deformation of the formed a’-martensite. These processes resulted in the presence of two phases in the structure of the steel with a definite crystallographic relationship and orientation changes of both phases with increasing of the deformation. Thus, the resultant deformation texture of the investigated steels is described by the austenite and martensite texture components. The rolling texture of γ-phase describes mainly orientations from the fiber α =<110>║ND and the major components of the martensite deformation texture are orientations from the fibers α1=<110>║RD and γ ={111}║ND.

Role of Heavy Deformation in Thermomechanical Processing on the Formation of Ultrafine-Grained Structure in Steels

2007 ◽  
Vol 558-559 ◽  
pp. 23-31 ◽  
Author(s):  
Tadashi Maki
Keyword(s):  
Cold Rolling ◽  
Thermomechanical Processing ◽  
High Carbon Steel ◽  
Point Of View ◽  
Matrix Phase ◽  
Second Phase ◽  
Two Phase ◽  
Ultrafine Grained Structure ◽  
Ultrafine Grained ◽  
Microduplex Structure

The formation of ultrafine-grained structure in steels by various thermomechanical processings is reviewed from a metallurgical point of view. In the recent new type TMCP, ultrafine ferrite grains with a grain size of about 1μm are obtained when the austenite is heavily deformed at lower temperatures. In this case, dynamic phenomena such as dynamic recrystallization become prominent in the process. In the aging after heavy cold rolling of supersaturated matrix phase in two-phase alloys, the competition between the recovery or recrystallization of matrix phase and the precipitation of second phase occurs, resulting in various types of two-phase structures including microduplex structure. Microduplex structure is also obtained by annealing after heavy cold rolling of coarse two-phase structure in duplex stainless steel and high carbon steel. Recently, various severe plastic deformation processings, in which very large plastic strain over 4 is applied to the materials, have been developed to produce ultrafine grained materials with nanocrystalline and/or submicrocrystalline structures.

Recent Advances in Gamma Titanium Aluminide Alloys

1990 ◽  
Vol 213 ◽  
Author(s):  
Young-Won (Y-W.) Kim
Keyword(s):  
Titanium Aluminide ◽  
Thin Plates ◽  
Second Phase ◽  
Two Phase ◽  
Gamma Titanium Aluminide ◽  
Gamma Titanium ◽  
The Matrix ◽  
Evolution Of Microstructure ◽  
Titanium Aluminide Alloys ◽  
Extended Discussion

ABSTRACTGamma titanium aluminide alloys of current interest are two-phase alloys consisting of γ-TiAl phase as the matrix and a α2-Ti3Al phase as the second phase. The properties of these alloys depend on alloy composition, processing, microstructure, and their combination. Two major microstructural constituents are gamma grains and lamellar grains, the latter of which contain alternate layers of gamma (γ) and alpha-2 (α2) thin plates. The relative amounts and distribution of these two constituents are the main factors controlling mechanical properties. This paper reviews our current understanding of the composition/microstructure/property relationships. An extended discussion will be made on the fundamental aspects of the formation of lamellar structure during cooling and the evolution of microstructure occurring during thermomechanical treatments.

scholarly journals 1300 K Compressive Properties of a Reaction Milled NiAl-AlN Composite

1990 ◽  
Vol 194 ◽  
Author(s):  
J. Daniel Whittenberger ◽  
Eduard Arzt ◽  
Michael J. Luton
Keyword(s):  
Stress Exponent ◽  
Nickel Aluminide ◽  
Thermomechanical Processing ◽  
Hot Isostatic Pressing ◽  
Small Diameter ◽  
Hot Extrusion ◽  
Second Phase ◽  
Strain Rates ◽  
Reaction Milling ◽  
The Matrix

AbstractCryomilling (high intensity mechanical ball milling in a liquid nitrogen bath) of the B2 crystal structure nickel aluminide leads to a NiAl-AlN composite containing about 10 vol pct second phase which is dispersed as very small diameter (< 50 nm) AlN particles in a mantle surrounding particle-free NiAl grains. The AlN particles are the result of reaction milling, where nitrogen incorporated into the matrix during cryomilling reacts with Al during subsequent thermomechanical processing to form a composite. Compressive testing at 1300 K of such materials densified by either hot extrusion or hot isostatic pressing have indicated that strength at relatively fast strain rates (>10−7 s−1 ) is dependent on the method of consolidation; however no clear dependency on densification technique appears to exist at slower rates. In addition deformation at 1300 K occurs by two distinct mechanisms, where at high strain rates the stress exponent is greater than 13 while at slower rates (< 10−7 s−1) a much lower stress exponent (∼6) was found.

scholarly journals Mechanism of Orientation Selectivity During Grain Growth of Secondary Recrystallization in Fe-3%Si Alloy

1999 ◽  
Vol 32 (1-4) ◽  
pp. 137-151 ◽  
Author(s):  
Y. Ushigami ◽  
T. Kubota ◽  
N. Takahashi
Keyword(s):  
Grain Growth ◽  
Secondary Recrystallization ◽  
Orientation Distribution ◽  
Recrystallization Temperature ◽  
Second Phase ◽  
Average Deviation ◽  
Pinning Effect ◽  
Second Phase Particles ◽  
The Matrix ◽  
The Ideal

Selective growth of {110}〈001〉 grains in the temperature gradient annealing has been studied in Fe–3%Si alloy. As grains grow, the average deviation angle from the ideal {110}〈001〉 orientation becomes smaller and orientation distribution changes corresponding to that of coincidence grains in the matrix. Secondary recrystallization temperature depends on the orientation of secondary recrystallized grain and sharper {110} 〈001〉 grains grow preferentially at lower temperatures.These phenomena are explained by modified Hillert's model of grain growth. Interfacial energy of coincidence boundary is lower than that of general boundary. Therefore, sharper {110}〈001〉 grains, which have higher frequency of coincidence grains in the primary recrystallized matrix, suffer lower pinning effect from the second phase particles and thus grow preferentially at lower temperatures.

Phase Transformation Textures in Ti-6Al-4V Alloy

2005 ◽  
Vol 495-497 ◽  
pp. 681-686 ◽  
Author(s):  
Sven C. Vogel ◽  
D. Bhattacharyya ◽  
G.B. Viswanathan ◽  
D.J. Williams ◽  
H.L. Fraser
Keyword(s):  
Orientation Relationship ◽  
Room Temperature ◽  
Volume Fraction ◽  
Turbine Blades ◽  
Large Body ◽  
Orientation Distribution ◽  
Distribution Functions ◽  
Transformation Mechanism ◽  
Two Phase ◽  
Crystal Direction

Titanium alloys are widely used in various industrial, domestic, and medical applications such as turbine blades, bicycle frames, knee implants, etc. The two-phase titanium alloy Ti-6Al-4V (wt. percent) is considered to be a workhorse alloy for many applications in these diverse fields. Despite the large body of work on this alloy, the question of the transformation mechanism from the hcp a to the bcc b phase, occurring on heating to temperatures above the a/b transus at ~980°C, is still unresolved. Due to experimental difficulties, it has not yet been clearly determined whether the increase in b volume fraction occurs by fresh nucleation of b crystals within a phase grains or the growth of preexisting b grains. Since the Burgers orientation relationship holds only if the b grains are nucleated within the a grains, the outcome of this question greatly affects texture-modeling efforts for this system. The Burgers orientation relationship predicts that the {0001} crystal direction in a grain of the a phase becomes a {110} crystal direction in a grain of the b phase after the transformation. In this work we present experimental results from in-situ texture measurements performed on the HIPPO neutron diffractometer at LANSCE. Using the combination of time-offlight neutrons and full-pattern Rietveld analysis allowed us to determine the orientation distribution functions of both phases at room temperature, 800°C, 1020°C and again at room temperature. We found strong indications that the b phase indeed grows from grains preexisting at room temperature. Upon re-transformation from b to a we found that the Burgers relationship is followed.

Finite Element Simulation Analysis of Multi-Stands Three-Roller Cold Rolling Process for Double Metal Composite Seamless Steel Tube

2013 ◽  
Vol 470 ◽  
pp. 197-204 ◽  
Author(s):  
Xian Kang Wang ◽  
Jin Duo Ye ◽  
Xu Ma ◽  
Qian Qian Tian ◽  
Xue Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Cold Rolling ◽  
Rolling Process ◽  
Steel Tube ◽  
Metal Composite ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Seamless Steel Tube ◽  
Seamless Steel

The numerical simulation of the Y-type three-roller two stands cold rolling stainless steel/carbon steel double metal composite seamless steel tube process was conducted through the finite element analysis of the elastic-plastic by applying the MSC.MARC software. Based on the numerical simulation, the character of stress and strain distribution parameters during the Y-type three-roller two stands cold rolling were obtained by the finite element analysis, and acquired the section pass deformation figure. The distribution of the axial stress, circle stress and radial stress were drawn below the Y-type mill along the circle. The mechanism of the tube cold rolling process and the effect of the forming steel tube both the diameter and wall thickness accuracy were explained according to the stress distribution. The results of the research can be applied to the design of the technical parameters in the forming process.

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