Semisolid Microstructural Evolution of Equal Channel Angular Extruded Mg-Al Alloy During Partial Remelting

2008 ◽  
Vol 141-143 ◽  
pp. 557-562 ◽  
Author(s):  
S.M. Liang ◽  
Rong Shi Chen ◽  
En Hou Han
Keyword(s):  
Solid Solution ◽  
Microstructural Evolution ◽  
Equal Channel Angular Extrusion ◽  
Isothermal Holding ◽  
Solution Treatment ◽  
Solid Particles ◽  
Al Alloy ◽  
Semisolid State ◽  
Effects Of Temperature ◽  
Spherical Grains

Using equal channel angular extrusion (ECAE) process, which combine the advantages of grain refinement and induced strain, for preparing semisolid billets is a relatively new Strain Induced Melt Activation(SIMA)method. This paper investigates the remelting and semisolid isothermal holding behavior of Mg-9Al alloy after ECAE processing at 350°C. It has been found that 2 passes ECAE-ed billets are qualified for obtaining spherical grains after remelting and isothermal holding treatment. Increasing the ECAE process from 2 passes to 8 passes has no further significant effects on the size and roundness of the solid particles at the semisolid state. The effects of temperature and isothermal holding time on microstructural evolution have also been investigated. In addition, the solid solution treatment before the ECAE processing affected greatly on microstructural evolution of the alloy during ECAE processing and thus the following remelting and isothermal holding behavior. The Mg17Al12 precipitates were uniformly decomposed from the saturated solid solution in the solutionized samples during ECAE processing. The coalescence of grains together with the self-blocking effect generated more entrapped liquid in the solutionized sample at semisolid state. Moreover, the solid particles of solutionized samples have bigger size and grow faster, which are detrimental to SSM processability.

scholarly journals The formation mechanism of the lamellar phase precipitated during solid solution treatment in the Mg-Gd-Al alloy

2020 ◽  
Vol 9 (5) ◽  
pp. 11392-11401
Author(s):  
Yongpeng Zhuang ◽  
Pengwen Zhou ◽  
Hongxia Wang ◽  
Kaibo Nie ◽  
Yiming Liu ◽  
...  
Keyword(s):  
Solid Solution ◽  
Formation Mechanism ◽  
Solution Treatment ◽  
Lamellar Phase ◽  
Al Alloy ◽  
Solid Solution Treatment

scholarly journals Optimization of a Solution Treatment in the Al-Cu-Mg-Ag Alloy via a Microstructural Investigation

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 66
Author(s):  
Hyeongsub So ◽  
Jae-Hong Shin ◽  
Leeseung Kang ◽  
Chanuk Jeong ◽  
Kyou-Hyun Kim
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Grain Growth ◽  
Microstructural Evolution ◽  
Precipitation Hardening ◽  
Solution Treatment ◽  
Solution Temperature ◽  
Al Alloy ◽  
Microstructural Investigation ◽  
Large Particles

We investigated the effect of solution temperature (Tsol. = 440–530 °C) on the mechanical properties of the Al–3.4Cu–0.34Mg–0.3Mn–0.17Ag alloy, finding that the investigated Al alloy showed the highest mechanical strength of σUTS = ~329 MPa at a Tsol. value of 470 °C. The microstructural investigation demonstrates that the mechanical properties for different Tsol. values stem from grain growth, precipitation hardening, and the formation of large particles at the grain boundaries. On the basis of Tsol. = 470 °C, the effect of each microstructural evolution is significantly different on the mechanical properties. In this study, the relationships between the microstructural evolution and the mechanical properties were investigated with respect to different values of Tsol.

HRTEM Analysis of Aging Electrolytic Low-Ti Al Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 1015-1020
Author(s):  
Wen Yan Wang ◽  
Jing Pei Xie ◽  
Wei Li ◽  
Zhong Xia Liu
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Electron Microscope ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Tensile Fracture ◽  
Al Alloy ◽  
Mg2si Phase ◽  
Β Phase ◽  
Precipitated Phases

Electronic tensile testing, scanning electron microscope, transmission electron microscope, X-ray diffractometer and high resolution transmission microscope were employed to investigate the mechanical properties, microstructure, tensile fracture and morphology of the precipitated phases of an electrolytic low-titanium wrought 6009 aluminum alloy. Results showed that the mechanical properties of the electrolytic aluminum sheet were improved by solid solution treatment incorporating with pre-aging treatment. The tensile strength and extensibility were enhanced by a factor of 23% and 38% by pre-aging treatment at 150 °C for 5 minutes respectively; a large quantity of nucleation sites of β˝ phase were generated by pre-aging treatment, which was propitious to the transformation from solid solution state to GP zone, and the stable size of GP zone formed during the pre-aging process promoted the precipitation of Mg2Si phase. The Mg2Si phase was revealed by HRTEM and the crystalline stripes were obtained by Fourier transformation.

A Study on the Nucleation Mechanism of Nano-Scale Precipitates of 7055 Aluminum Alloy

NANO ◽  
2017 ◽  
Vol 12 (12) ◽  
pp. 1750147
Author(s):  
Ping Zhang ◽  
Youqiang Wang
Keyword(s):  
Solid Solution ◽  
Aluminum Alloy ◽  
Microstructural Evolution ◽  
Solution Treatment ◽  
Age Hardening ◽  
Orientation Relation ◽  
Nucleation Mechanisms ◽  
The Matrix ◽  
7055 Aluminum Alloy ◽  
Al Matrix

7055 aluminum alloy is a typical age-hardening alloy whose properties change with microstructural evolution as a result of heat treatment. In this paper, the microstructural evolution of the alloy after solid solution treatment and manual aging is examined using SEM, TEM and HADDF. The precipitation, nucleation and growth mechanisms of [Formula: see text] and [Formula: see text] phases are also analyzed. Results show that, as aging proceeds, the Al–Cu phase gradually enlarges and thickens the following precipitation sequence of supersaturated solid solution (SSSS) [Formula: see text] GPI zone [Formula: see text] GPII zone [Formula: see text] phase [Formula: see text] phase; some [Formula: see text] phases formed during aging, which have two different nucleation mechanisms: homogeneous nucleation and heterogeneous nucleation, the [Formula: see text] phases of the latter being marginally larger in size than those of the former. There is a transition in the transformation of (Al3Cu) in GPII zone into [Formula: see text]-phase (Al2Cu). The orientation relation between [Formula: see text] phase and Al matrix is (100)Al//(100)[Formula: see text], (010)Al//(010)[Formula: see text], (001)Al//(001)[Formula: see text]. According to this relationship, [Formula: see text] phase has three variants in the matrix: Variants 1, 2, and 3, which represent the [Formula: see text] phase along {100}Al, {010}Al and {001}Al. As [Formula: see text] phase has a special orientation relation with Al matrix (100)Al//(100)[Formula: see text], (010)Al//(010)[Formula: see text], (001)Al//(001)[Formula: see text], [Formula: see text] phase is distributed in disc form on {001}Al. Significantly larger [Formula: see text] phase can be observed. The orientation relation between S phase and Al matrix is [100]Al//[100]S, [021]Al//[010]S, [012]Al//[001]S. [Formula: see text] phase grows in step form for a period equaling to 1.75-fold unit cell of [Formula: see text]. As [Formula: see text] phase grows, the Cu atoms segregated on the edge of [Formula: see text] phase are gradually consumed.

Microstructural Evolution of Solid-solution-treated Zn–22Al in the Semisolid State

2013 ◽  
Vol 29 (8) ◽  
pp. 765-774 ◽  
Author(s):  
M.A.M. Arif ◽  
M.Z. Omar ◽  
N. Muhamad ◽  
J. Syarif ◽  
P. Kapranos
Keyword(s):  
Solid Solution ◽  
Microstructural Evolution ◽  
Semisolid State ◽  
Solution Treated

Microstructural Evolution of 7A04 Alloy Prepared by FE-ECAE in Semi-Solid State

2010 ◽  
Vol 426-427 ◽  
pp. 274-278 ◽  
Author(s):  
Wen Tong Tian ◽  
H. Yang ◽  
X. Cao
Keyword(s):  
Microstructural Evolution ◽  
Equal Channel Angular Extrusion ◽  
Volume Fraction ◽  
Isothermal Holding ◽  
Great Influence ◽  
Equivalent Strain ◽  
Main Mechanism ◽  
Isothermal Treatment ◽  
Liquid Volume ◽  
Semi Solid

In the paper, forward extrusion-equal channel angular extrusion (FE-ECAE), which is new strain-induced melt activation (SIMA) method, is introduced in making semi-solid billet of 7A04 alloy. The principle of the method is that by using FE-ECAE as strain induced step and semi-solid isothermal treatment as melt activation step. The results show that semi-solid billet with highly spheroidal and homogeneous refined grains can be prepared by FE-ECAE method. The equivalent strain in FE-ECAE before reheating has a great influence on its microstructural evolution. Grain size decreases and its shape also approaches to sphericity with increasing equivalent strain. The main mechanism of the initial semi-solid grains coarsening was coalescence. With the prolongation of isothermal holding time, the grains grew up and spheroidized, in which the mean diameter of grain and liquid volume fraction increased. In the meantime, the higher the reheating temperature, the faster the grain grew and spheroidized. Subsequently, the main mechanism of grains coarsening was Ostwald ripening. The suitable reheating temperature of 7A04 alloy was 610°C.

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