scholarly journals Influence of the Precipitation of Secondary Phase on the Thermal Diffusivity Change of Al-Mg2Si Alloys

2018 ◽  
Vol 8 (11) ◽  
pp. 2039 ◽  
Author(s):  
Yu-Mi Kim ◽  
Se-Weon Choi ◽  
Young-Chan Kim ◽  
Chang-Seok Kang ◽  
Sung-kil Hong
Keyword(s):  
Thermal Diffusivity ◽  
Aging Treatment ◽  
Secondary Phase ◽  
Precipitation Behavior ◽  
Scanning Calorimetry ◽  
Heat Flow Curve ◽  
Mg2si Phase ◽  
Β Phase ◽  
Treatment Conditions ◽  
The Matrix

Al-Si-Mg alloys are investigated to determine the relationship between changes in the thermal diffusivity and precipitation behavior of the Mg2Si phase with various contents of Mg2Si and aging treatment conditions. The samples were solid solution-treated and then quenched with water (80 °C). Aging treatments were implemented at temperatures ranging from 180 to 240 °C for 5 h. The precipitation behavior of Mg2Si was observed using a heat flow curve using differential scanning calorimetry analysis. The thermal diffusivity of Al-Mg2Si alloy was affected by the precipitation of the Mg2Si phase, particularly in the meta-stable β phase. In the temperature range of precipitation occurrence, the thermal diffusivity of the alloy increased with the temperature when the precipitation of the meta-stable β phase of the sample was incomplete. However, at the same temperature, the samples in which precipitation had completed did not have any increased thermal diffusivity. The thermal diffusivity of the samples decreased when the meta-stable Mg2Si phase had dissolved in the matrix. The precipitation and dissolution of Mg2Si mainly affected the variation of thermal diffusivity in Al-Si-Mg. In contrast, the stable Mg2Si phase was not affected by changes in thermal diffusivity at a high temperature.

scholarly journals Influences of Heat Treatment on the Thermal Diffusivity and Corrosion Characterization of Al-Mg-Si alloy

2021 ◽  
Vol 59 (8) ◽  
pp. 582-588
Author(s):  
Yu-Mi Kim ◽  
Se-Weon Choi ◽  
Young-Chan Kim ◽  
Chang-Seog Kang
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Thermal Diffusivity ◽  
Corrosion Rate ◽  
Aging Treatment ◽  
Solute Concentration ◽  
Scanning Calorimetry ◽  
Mg2si Phase ◽  
Solution Treated ◽  
Treated Sample

The effect of the heat treatment on the Mg2Si phase in Al-Mg-Si alloy was investigated by a laser flash apparatus (LFA), Differential scanning calorimetry (DSC) and corrosion test. The alloy samples were solution treated at 590 oC for a half hour followed by warm water quenching, and then aged in air at 180, 200 and 240 oC for 5 hours. The results showed that the corrosion resistance of the solid solution treated sample was more improved than the as cast sample. Aging treatment also helped increase corrosion resistance at room temperature. It is thought that the fine Mg2Si precipitation phase on the grain had a more positive effect on improving corrosion resistance than crystallization of the Mg2Si phase on the grain boundaries. Corrosion rate also decreased with increasing aging treatment. The corrosion rate of AT240 was reduced to 1.16 MPY compared with the AT180 test piece, which had a corrosion rate of 3.79 MRY. The solution treated sample also showed lower thermal diffusivity than the aged samples. The thermal diffusivity increased as the solute concentration of Mg and Si in the a-Al matrix rapidly decreased during aging treatment. On the other hand, the thermal diffusivity of the aged samples, in which precipitation was completed by the aging process, decreased as the temperature rose. The thermal conductivities of all samples were similar near 250 oC when the β'' phase and β' precipitation was completed.

Microstructure and Mechanical Properties of a Cu-Pd-Ag Alloy Wire with Aging Treatment

2018 ◽  
Vol 941 ◽  
pp. 1167-1172
Author(s):  
Chihiro Iwamoto ◽  
Fumio Watanabe ◽  
Risei Koitabashi
Keyword(s):  
Electronic Device ◽  
Aging Treatment ◽  
Age Hardening ◽  
Nanoindentation Test ◽  
Alloy Wire ◽  
Hardening Mechanism ◽  
Β Phase ◽  
Α Phase ◽  
The Matrix ◽  
The Wire

Cu-Pd-Ag alloy is widely used in electronic device applications due to its relatively low electric resistance. To obtain higher strength wire, age-hardening is usually conducted to this alloy wire. However, the detailed hardening mechanism of Cu-Pd-Ag alloy was not clarified enough. In the present paper, we investigated the microstructure and hardness of the Cu-Pd-Ag alloy wire with aging treatment. Original alloy contained many rods with an Ag-rich α phase extended along the wire direction in a Cu-rich α phase matrix. After heat treatment of 623K with 1 hour, the matrix was transformed to the β phase contained many elongated α2 phases as nanolamellar structure. Many β’ phase precipitated in the rods. Hardness measured with nanoindentation test showed that the matrix had a higher value than that of the rods. In the Cu-Pd-Ag alloy wire, the nanolamellar structure of the matrix was revealed to contribute to the hardening of the wire.

scholarly journals Effects of the Mg/Si Ratio on Microstructure, Mechanical Properties, and Precipitation Behavior of Al–Mg–Si–1.0 wt %-Zn Alloys

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2591 ◽  
Author(s):  
Yong Li ◽  
Guanjun Gao ◽  
Zhaodong Wang ◽  
Hongshuang Di ◽  
Jiadong Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Solution Treatment ◽  
Hardness Test ◽  
Strengthening Effect ◽  
Precipitation Behavior ◽  
Scanning Calorimetry ◽  
First Choice ◽  
The Matrix ◽  
Zn Alloys

Aluminum alloys are widely used as first-choice materials for lightweight automotive applications. It is important that an alloy have a balance between strength and formability. In this study, the alloys were melted, cast, hot rolled, and cold rolled into 1 mm-thick sheets. The microstructure, mechanical properties, and precipitation behavior of Al–Mg–Si–1.0 wt %-Zn alloys with Mg/Si ratios of 0.5, 1, and 2 after solution treatment were studied using optical and electron microscopy, a tensile test, the Vickers hardness test, and differential scanning calorimetry. The results showed that a high density and number of Al–Fe–Si particles were observed in the matrix, thus causing the formation of more homogeneous and smaller recrystallized grains after treatment with the solution. In addition, a higher volume fraction of cubeND and P-types texture components formed during solution treatment. Also, a high r value and excellent deep drawability were achieved in the medium-Mg/Si-ratio alloy. The formation of denser strengthening precipitates led to a better paint-bake hardening effect in comparison with the other two alloys. Furthermore, the precipitation kinetics were enhanced by the addition of Si, and the addition of Zn did not alter the precipitation sequence of the Al–Mg–Si alloy. The dual-phase strengthening effect was not achieved in the studied alloys during paint-bake treatment at 175 °C.

MICROSTRUCTURE AND FRACTURE TOUGHNESS OF FeNiCr-TiC COMPOSITE PRODUCED BY THERMITE REACTION

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2904-2909
Author(s):  
WENJUN XI ◽  
CHAOLIANG SHI
Keyword(s):  
Fracture Toughness ◽  
Electron Microscope ◽  
Aging Temperature ◽  
Aging Treatment ◽  
Ferrite Matrix ◽  
Β Phase ◽  
Transmission Electron ◽  
The Matrix ◽  
Average Size ◽  
Effects Of Aging

The microstructures of the FeNiCr - TiC composite produced by the rapid solidification thermite process were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The effects of aging treatment on the microstructure and fracture toughness of the composite were examined. Results showed that the FeNiCr - TiC composite was composed of ferrite (α- FeNiCr ), TiC and NiAl (β phase). TiC particles in the matrix were in the shape of polygon and uniformly distributed, and their size was less than 3 µm. The β phase was coherent with the ferrite matrix, and its average size was about 50 nm. The fracture toughness of composite was 22 MPa·m1/2 without aging. When the aging temperature was below 600°C, the fracture toughness of the composite had higher plateau values and reached the maximum of 32 MPa·m1/2 at aging temperature 500°C due to the precipitation of NiAl phase on the nanometer scale. The fracture toughness decreased rapidly aged at 650°C, and then kept homology value in the range of 700 to 900°C, which was attributed to the precipitation of needle-shaped carbide ( Cr / Fe )7 C 3 at the grain boundaries.

scholarly journals 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

2016 ◽  
Vol 61 (2) ◽  
pp. 1235-1240 ◽  
Author(s):  
A. Urbańczyk-Gucwa ◽  
K. Radwański ◽  
K. Rodak
Keyword(s):  
Aging Treatment ◽  
Recovery Process ◽  
Scanning Transmission Electron Microscope ◽  
Second Phase ◽  
Electron Backscattered Diffraction ◽  
Treatment Conditions ◽  
Second Phase Particles ◽  
Scanning Transmission ◽  
The Matrix ◽  
Cyclic Movement

Abstract 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.

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.

Study on CO2 Laser Surface Hardening of 17-4PH Stainless Steel

2011 ◽  
Vol 239-242 ◽  
pp. 73-76
Author(s):  
Jun Wei Zhang ◽  
Gang Lei ◽  
Shu Chen Pan ◽  
Fa Yu Wu
Keyword(s):  
Stainless Steel ◽  
Phase Transformation ◽  
Aging Treatment ◽  
Secondary Phase ◽  
Hardened Layer ◽  
Laser Surface ◽  
Transformation Zone ◽  
Fine Grain ◽  
The Matrix ◽  
Surface Quenching

At present work, the microstructure and corresponding hardness of 17-4PH stainless steel were investigated by the process of CO2 laser surface quenching and aging treatment. The hardness of the phase transformation zone in the hardened layer was 433.2HV, higher than 378.1HV of the matrix, which was attributed to the fine-grain and solution strengthening after laser quenching. The hardness of the phase transformation zone increased further to 464.5HV after an aging treatment at 520°C due to the precipitation strengthening of fine secondary phase particles.

MICROSTRUCTURAL EVOLUTION OF Al-Cu-Mg-Ag ALLOY WITH TRACE Zr ADDITION DURING TWO-STEP HOMOGENIZATION

2009 ◽  
Vol 23 (06n07) ◽  
pp. 855-862 ◽  
Author(s):  
FEIYUE MA ◽  
ZHIYI LIU
Keyword(s):  
Melting Point ◽  
Grain Boundaries ◽  
Microstructural Evolution ◽  
Cast Alloy ◽  
Scanning Calorimetry ◽  
Zr Addition ◽  
Homogenization Time ◽  
The Matrix ◽  
Higher Temperature ◽  
Lower Temperature

The microstructural evolution in an Al - Cu - Mg - Ag alloy with trace Zr addition during homogenization treatment was characterized by Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray Spectroscopy (EDS). It was shown that the low-melting-point phase segregating toward grain boundaries is Al 2 Cu , with a melting point of 523.52°C. A two-step homogenization process was employed to optimize the microstructure of the as-cast alloy, during which the alloy was first homogenized at a lower temperature, then at a higher temperature. After homogenized at 420°C for 6 h, Al 3 Zr particles were finely formed in the matrix. After that, when the alloy was homogenized at an elevated temperature for a longer time, i.e., 515°C for 24 h, most of the precipates at the grain boundaries were removed. Furthermore, the dispersive Al 3 Zr precipitates were retained, without coarsening greatly in the final homogenization step. A kinetics model is employed to predict the optimal homogenization time at a given temperature theoretically, and it confirms the result in present study, which is 420°C/6h+515°C/24h.

scholarly journals The Effect of Aging on Precipitates, Mechanical and Magnetic Properties of Fe-21Cr-15Ni-6Mn-Nb Low Magnetic Stainless Steel

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 819
Author(s):  
Changsheng Li ◽  
Kun Li ◽  
Jingbo Dong ◽  
Jinyi Ren ◽  
Yanlei Song
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
Stainless Steel ◽  
Magnetic Properties ◽  
Solution Heat Treatment ◽  
Aging Treatment ◽  
Relative Magnetic Permeability ◽  
Coarsening Behavior ◽  
The Matrix ◽  
Coherent Orientation

The effect of aging on the precipitates, mechanical and magnetic properties of Fe-21Cr-15Ni-6Mn-Nb low magnetic stainless steel were investigated. The steel was aged at 550–750 °C for 2 h after solution heat treatment at 1100 °C for 1 h. During the aging treatment, the (Nb, V)(C, N) particles gradually precipitated in the grain, which were coherent or semi-coherent with the matrix. When the aging temperature was beyond 650 °C, the coarsening rate of (Nb, V)(C, N) particles increase rapidly and the coherent orientation between (Nb, V)(C, N) particles and the matrix was lost gradually. Meanwhile, coarse M23C6 was distributed at the grain boundary with chain shape, which was non-coherent with the matrix. The coarsening behavior of (Nb, V)(C, N) precipitates in the grain was analyzed, and the size of the particles precipitated after aging treatment at 650°C for different time was calculated and studied. After aging treatment at 650 °C for 2 h, the yield strength and tensile strength of the stainless steel was 705.6 MPa and 1002.3 MPa, the elongation and the relative magnetic permeability was 37.8% and 1.0035, respectively.

The Investigation on Aluminium Alloys Automobile Wheel with Low-Titanium Content Produced by Electrolysis

2005 ◽  
Vol 475-479 ◽  
pp. 317-320 ◽  
Author(s):  
Jing Pei Xie ◽  
Ji Wen Li ◽  
Zhong Xia Liu ◽  
Ai Qin Wang ◽  
Yong Gang Weng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Aluminium Alloys ◽  
Solution Treatment ◽  
A356 Alloy ◽  
Aging Treatment ◽  
Titanium Content ◽  
The Matrix ◽  
Automobile Wheel

The in-situ Ti alloying of aluminium alloys was fulfilled by electrolysis, and the material was made into A356 alloy and used in automobile wheels. The results show that the grains of the A356 alloy was refined and the second dendrites arm was shortened due to the in-situ Ti alloying. Trough 3-hour solution treatment and 2-hour aging treatment for the A356 alloy, the microstructures were homogeneous, and Si particles were spheroid and distribute in the matrix fully. The outstanding mechanical properties with tensile strength (σb≥300Mpa) and elongation values (δ≥10%) have been obtained because the heat treatment was optimized. Compared with the traditional materials, tensile strength and elongation were increased by 7.6~14.1% and 7.4~44.3% respectively. The qualities of the automobile wheels were improved remarkably.

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