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.

Effect of heat treatment on microstructure and corrosion resistance of extruded ZK80 Mg alloy

2019 ◽  
Vol 9 (9) ◽  
pp. 1092-1099
Author(s):  
Fenghong Cao ◽  
Chang Chen ◽  
Zhenyu Wang
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Aging Time ◽  
Room Temperature ◽  
Aging Treatment ◽  
Corrosion Process ◽  
Corrosion Mechanism ◽  
Nacl Solution ◽  
Corrosion Properties

The corrosion characteristics and corrosion mechanism of the extruded ZK80 alloy with different states soaking in 3.5% NaCl solution at room temperature were analyzed via OM, SEM, EDS, XRD and static weightlessness method and other experimental analysis methods. The results show that when the aging temperature is constant, and the corrosion rate decreases with the lengthen of aging time, while when the corrosion time is constant, the corrosion rate increases with the increase in aging time. Appropriate aging treatment not only refines the grain of the alloy, but also precipitates the Mg–Zn phase which can effectively prevent the corrosion process and improve the anti-corrosion properties of the alloy. The main corrosion characteristics of the alloy are filamentary corrosion and pitting corrosion.

Research on Mechanical and Corrosion Properties of Ti-Microalloyed Biomedical Cobalt-Based Alloy

2016 ◽  
Vol 852 ◽  
pp. 1168-1174
Author(s):  
Ya Ting Cao ◽  
Feng Wang ◽  
Qing Xuan Ran ◽  
Yu Lai Xu ◽  
Jun Li ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Phase Transformation ◽  
Aging Treatment ◽  
Physiological Saline ◽  
Corrosion Properties ◽  
Solution Treated ◽  
Cast Specimen ◽  
Mechanical And Corrosion Properties ◽  
Stable Passive

0.15 wt. % Ti-microalloyed Co-28.5Cr-5.9Mo-0.27C alloy has been developed by examining the effect of solution and aging treatment on microstructure, mechanical and corrosion properties. The results showed that elongation of the cast specimen were lower than 8%, while reached 18% after solution-treated at 1220 °C for 4 h. Phase transformation from austenite to martensite was observed after aging at 800°C and the amount of transformed martensite increased with aging time. Polarization tests of the samples after solution and aging treatment were carried out in physiological saline at 37 °C, which showed a stable passive film formed on the surface and no apparent pitting phenomenon occurred on the specimens, which indicated that heat treatment has not significant influence on the corrosion resistance of Co-Cr-Mo-0.27C-0.15Ti alloy.

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 Effect of Heat Treatment and Sulfuric Acid Anodization on Corrosion Resistance of Aluminum Alloy (AA7075)

2021 ◽  
Vol 40 (1) ◽  
pp. 56-62
Author(s):  
M. Abdullahi ◽  
L.S. Kuburi ◽  
P.T. Zubairu ◽  
U. Jabo ◽  
A.A. Yahaya ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Sulfuric Acid ◽  
Corrosion Rate ◽  
Polarization Resistance ◽  
Testing Machine ◽  
Palm Kernel ◽  
Engine Oil ◽  
Micro Hardness

This paper, studied the effect of heat treatment and anodization on corrosion resistance of aluminum alloy 7075 (AA7075), with a view to improving its corrosion resistance. Microstructure and micro hardness of the anodic film of the samples were studied with the aid of optical metallurgical microscope and automated micro hardness testing machine. Linear polarization methods were used to assess the corrosion behaviour of the alloy in 0.5M HCl. The microstructure of the annealed sample showed formation of dendrites while precipitation hardened samples in palm kernel oil and SAE 40 engine oil showed precipitates of MgZn2. The SEMS result showed pores and micro cracks on the surfaces of the anodized samples, with the as cast and anodized sample in sulfuric acid exhibiting most compact with few pores. The as cast and sulfuric acid anodized sample shows highest micro hardness value of 205.33 HV, while the least value of 150.67 HV was recorded in sample precipitation hardened in SAE 40 engine oil and anodized in sulfuric acid. Analysis of the potentiodynamic polarization data and curves showed a linear relationship (decrease in icorr, decreases the corrosion rate) between current density and the corrosion rate in all the samples. Higher polarization resistance of 15.093 Ω/cm2 was recorded by the as cast and Sulfuric acid (SA) anodized sample while the precipitation treated in SAE 40 engine oil plus SA anodized sample recorded lowest polarization resistance of 5.2311 Ω/cm2. Heat treatment alone improves corrosion resistance of AA 7075 in 0.5 M HCl solution but heat treatment plus SA anodization does not improve corrosion resistance in the same environment.

Influences of Zinc Content and Solution Heat Treatment on Microstructure and Corrosion Behavior of Mg-Zn Binary Alloys

CORROSION ◽  
10.5006/3672 ◽  
2020 ◽  
Author(s):  
Dinh Pham ◽  
Sachiko Hiromoto ◽  
Equo Kobayashi
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Volume Fraction ◽  
Galvanic Corrosion ◽  
Zinc Content ◽  
Eutectic Cell ◽  
Zn Content ◽  
Cast Alloys

The influences of Zn content and heat treatment on microstructure and corrosion behavior of Mg-xZn (x=1, 3, 5 and 7 wt.%) alloys were studied. (α-Mg + MgZn) eutectic cells and Zn-segregated regions were formed in the as-cast alloys. The Zn-rich phases acted as micro-cathodes in galvanic corrosion. Volume fraction of the Zn-rich phases increased with Zn content of the as-cast alloys, leading to a decrease in corrosion resistance. The corrosion rate of the as-cast alloys increased by 4 times with an increase of the volume fraction of eutectic cell from 0.07 vol.% of Mg-1Zn alloy to 2.18 vol.% of Mg-5Zn alloy. The corrosion rate of Mg-7Zn alloy with 2.87 vol% eutectic cells was 2 times higher than that of Mg-5Zn alloy. The Zn-rich phases dissolved by the T4 treatment and only the T4-treated Mg-7Zn alloy obviously showed eutectic cells of 1.73 vol.%. The polarization resistance (Rp) of the T4-treated Mg-1, 3 and 5Zn alloys was 2-10 times higher than that of the as-cast alloys. The T4-treated Mg-7Zn showed similar Rp to the as-cast Mg-5Zn alloy. Consequently, the volume fraction of Zn-rich phases dominated the corrosion resistance of Mg-xZn alloys.

Investigation on the Influence of Precipitated Phase on Corrosion Resistance of the Ni-Based Alloys

2012 ◽  
Vol 184-185 ◽  
pp. 1038-1043
Author(s):  
Xue Hui Zhao ◽  
Zhen Quan Bai ◽  
Yao Rong Feng ◽  
An Qing Fu
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Corrosion Resistance ◽  
Electron Microscope ◽  
Grain Boundaries ◽  
Aging Treatment ◽  
Treatment Temperature ◽  
Different Temperatures ◽  
Metallographic Observation ◽  
Precipitated Phases

The influence of precipitated phases in Ni-based alloys during solid solution aging treatment on the performance of Ni-based alloys was investigated by means of metallographic observation, scanning electron microscope (SEM), and transmission electron microscope (TEM). The variation of microstructure and resultant phases as a result of solid solution aging treatment at different temperatures was discussed. The results show that the heat treatment temperature has significant influences on the type as well as quantity of precipitation phases. Lots of phases precipitated at grain boundaries, the distribution of precipitated phases are characterized by mesh-like structure. The corrosion tests results indicate that there is a potential difference between grains and grain boundaries due to the precipitation of chrome carbide at grain boundaries, resulting in pitting corrosion occurred preferentially at grain boundaries, consequently, the corrosion resistance of Ni-based alloys is reduced. In order to enhance the corrosion resistance of Ni-based alloys, it is expected to control the carbon content in a lower range and proper heat treatment process to avoid large amount precipitation of chrome carbide.

Effect of Solution Treatment on Corrosion Resistance of the Biodegradable NZ20K Alloy

2016 ◽  
Vol 849 ◽  
pp. 196-202
Author(s):  
Yang Fei ◽  
Xiao Bo Zhang ◽  
Zhi Xin Ba ◽  
Zhang Zhong Wang
Keyword(s):  
Corrosion Resistance ◽  
Electron Microscope ◽  
Corrosion Rate ◽  
Scanning Electron Microscope ◽  
Biomedical Applications ◽  
Solution Treatment ◽  
Solution Temperature ◽  
Solution Treated ◽  
Different Temperatures ◽  
Scanning Electron

In order to study the effect of solution temperature on corrosion resistance of Mg alloy for biomedical applications, microstructure and corrosion behavior of Mg-2.25Nd-0.11Zn-0.43Zr (NZ20K) alloy solution treated at different temperatures were investigated by using a scanning electron microscope (SEM) equipped with an electron dispersive spectroscope (EDS), electrochemical and mass loss tests. The results show that the grains grow and precipitations decreases with increasing the solution temperature. The corrosion rate decreases firstly and then increases with increasing solution temperature, and the best corrosion resistance of the NZ20K alloy is obtained at the temperature of 540 °C.

Influence of Various Heat Treatment on Corrosion Resistance of As-Extruded Mg-9Li-3Al-2.5Sr Alloys

2014 ◽  
Vol 788 ◽  
pp. 41-44 ◽  
Author(s):  
Yuan Qing Yu ◽  
Xiao Dong Peng ◽  
Hong Yu Yi ◽  
Jun Wei Liu
Keyword(s):  
Corrosion Resistance ◽  
Intermetallic Compounds ◽  
Unit Volume ◽  
Aging Treatment ◽  
Corrosion Current ◽  
Immersion Test ◽  
Corrosion Process ◽  
Nacl Solution ◽  
Boundary Area ◽  
Solution Treated

The corrosion behavior of Mg-9Li-3Al-2.5Sr alloy, solution treated at 400°C for 3h with various aging temperature (Ta; Ta=75,100,125,150,175°C), was investigated in 3.5% NaCl solution by immersion test and polarization curve measurement. Experimental results suggest that the alloy aged at150°Cfor 6h exhibits the highest corrosion resistance while the alloy treated at 75°C for 6h presents lowermost corrosion resistance. The corrosion resistance of the alloy is related to the grain size and the distribution of Al4Sr compound. The segregation of intermetallic compounds can accelerate the corrosion process. It was found that duo to the proper solid-solution and aging treatment, intermetallic compounds were distributed evenly along the grain boundaries, which can reduce the corrosion rate and corrosion current. In addition,with the growth of grain, the decrease of the grain boundary area per unit volume lead to improvement of corrosion resistance of the alloys.

Effect of Heat Treatment on the Corrosion Resistance of Cast Mg-7.3Al Alloy

2010 ◽  
Vol 146-147 ◽  
pp. 585-588
Author(s):  
Su Qiu Jia ◽  
Guo Jun Liu ◽  
Qi Shuang Chen
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Microstructural Characterization ◽  
Main Role ◽  
Β Phase

Mg-7.3Al magnesium alloys were investigated in the paper. The paper presents microstructural characterization of Mg-7.3Al alloy after casting and heat treatment. The casting temperature was 740°C and heat treatment was performed at 420 °C for 24 h with aging at 180 °C for 8h,16h,24h. The microstructure of the casting alloy consists of α-Mg phase matrix with a primary β phase (Mg17Al12) at grain boundaries. After solution treatment β phases were soluted in α-Mg phase matrix . Aging treatment caused β phases precipitation. The corrosion resistance of magnesium alloy was determined in 3.5 % NaCl by immersion tests and polarization curves. The results shows that the corrosion resistance of magnesium alloy after solution treat is the best than that of the others heat treatment in polarization curve tests and the samples with aging for 16h and 24h presents higher corrosion resistance than those with solution and aging for 8h in immersion tests. Solution treatment plays a main role for corrosion resistance of Mg-7.3Al magnesium alloy in short term corrosion, but more continuous β phases in Mg-7.3Al alloy after ageing act as a barrier and play a main role in long term corrosion.

Influence of Heat Treatment on Martensitic Transformations in Copper-Based Alloys with Shape Memory Effect

2016 ◽  
Vol 869 ◽  
pp. 474-478
Author(s):  
Luiz Carlos Sekitani da Silva ◽  
Cezar Henrique Gonzalez ◽  
Carlos Augusto do Nascimento Oliveira ◽  
Karla Carolina Alves da Silva
Keyword(s):  
Heat Treatment ◽  
Shape Memory ◽  
Thermal Hysteresis ◽  
Martensitic Transformations ◽  
Scanning Calorimetry ◽  
Critical Temperatures ◽  
Heat Treated Sample ◽  
Heat Treated ◽  
Treated Sample ◽  
Shape Memory Effects

In the present work the copper base alloys with shape memory effects were characterized. The alloys were subjected to three different heat treatments that promoted changes in characteristics of thermoelastic martensitic transformation (transformation temperatures, thermal hysteresis and enthalpies of transformation). The alloys have their microstructures characterized by optical and scanning electron microscopy. Microhardness tests were performed. Differential scanning calorimetry (DSC) was used to evaluate the transformation critical temperatures of alloy and the transformation enthalpies for each heat treated sample. Thermoelastic properties have changed for each heat treatment. In the micrographs of the heat-treated samples was possible to observe the microstructure of the martensitic phase characteristic. They show the presence of martensite platelets (needles) self-accommodation.

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