Age-Hardening Behavior of Mg-Al-Zn Alloys Produced by Sand Mold Casting

2014 ◽  
Vol 783-786 ◽  
pp. 467-471
Author(s):  
Seiji Saikawa ◽  
Yuhei Ebata ◽  
Kiyoshi Terayama ◽  
Susumu Ikeno ◽  
Emi Yanagihara
Keyword(s):  
Magnesium Alloy ◽  
Aging Temperature ◽  
Volume Fraction ◽  
Discontinuous Precipitation ◽  
Sand Mold ◽  
Age Hardening ◽  
Aged Sample ◽  
Maximum Hardness ◽  
Continuous Precipitation ◽  
Hardening Behavior

In recent years, Mg-Al-Zn system alloy has been used for the parts in the automobile for weight reductions. The age-hardening behavior of Mg-6mass%Al (-1mass%Zn)-0.3mass%Mn alloys sand mold castings were investigated by Vickers hardness measurement and optical microscopic observation. Both alloys were solution-treated and then isothermal-aged at 473, 498 and 523K. For each aging temperature, both alloys were indicated age-hardening obviously, and decreased the value of maximum hardness and shorten time to maximum hardness with heighten aging temperature. Age-hardening curves for both alloys approximately showed the same change of hardness. However, these optical micrographs after aging treatment are observed different microstructure. In case of AM60 magnesium alloy, discontinuous precipitation preferentially occurred in aged sample. The volume fraction of discontinuous precipitation was larger than that of continuous precipitation. On the other hand, in case of AZ61 magnesium alloy, the volume fraction of continuous precipitation was larger than that of discontinuous precipitation. Furthermore, over-aged sample of both alloys were consisted of discontinuous precipitation, continuous precipitation and pre-precipitation area.

Effect of Grain Size on Microstructure and Aging Behavior in AM60 Magnesium Alloy

2011 ◽  
Vol 409 ◽  
pp. 373-378
Author(s):  
H. Takano ◽  
Mitsuaki Furui ◽  
Susumu Ikeno ◽  
Tomoyasu Yamaguchi ◽  
Seiji Saikawa
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Grain Boundary ◽  
Eutectic Reaction ◽  
Age Hardening ◽  
Peak Hardness ◽  
Aging Behavior ◽  
Continuous Precipitation ◽  
Hardening Behavior ◽  
Average Grain Size

Our recent studies showed that continuous and cellular precipitates are covered with the whole of crystal grain in age hardable AM60 magnesium alloy cast into permanent molds, which have the average grain size of 75-85μm. Also, continuous precipitation is generated nearby grain boundary in the same alloys cast into sand molds, which have the average grain size of 138-147μm. It’s thought that permanent mold castings have the age hardening behavior of intragranular precipitation participation type that is influenced by continuous precipitates. It’s also thought that sand mold castings have the age hardening behavior of grain boundary participation type that is influenced by cellular precipitates. In this study, AM60 magnesium alloy with larger grain size was used to detect the grain size dependence of microstructure and aging behavior. In the microstructure of as-cast condition, the larger the grain size, it was shown that the none-equilibrium crystallized β phase with eutectic reaction during the solidification between liquidus and solidus temperatures becomes large-size. In the age hardening curves, the peak hardness values become higher with decreasing of grain size.

Discontinuous and Continuous Precipitation during Aging in Mg-Al System Alloys

2011 ◽  
Vol 409 ◽  
pp. 329-334
Author(s):  
Yuhei Ebata ◽  
Mitsuaki Furui ◽  
Susumu Ikeno ◽  
Katsuya Sakakibara ◽  
Seiji Saikawa
Keyword(s):  
Aging Temperature ◽  
Aluminum Content ◽  
Hardness Measurement ◽  
Al Alloys ◽  
Age Hardening ◽  
Content Increase ◽  
Maximum Hardness ◽  
Continuous Precipitation ◽  
Solution Treated ◽  
Lower Aging Temperature

In this study, age-hardening behavior of Mg-Xmass%Al alloys (X=3, 4.5, 6, 7.5 and 9mass%) were investigated by Vickers hardness measurement and optical microscopic observation. Each alloy was solution-treated and then isothermal-aged at 473, 498 and 523K. In the case of aluminum content less than 6mass%, Mg-3mass%Al and Mg-4.5mass%Al alloys, occurred insignificant age hardening. In the case of aluminum content higher than 6mass%, Mg-6mass%Al, Mg-7.5mass%Al and Mg-9mass%Al alloys, occurred remarkable age hardening. For each aging temperature, with heighten aluminum content, increase the value of maximum hardness and shorten time to maximum hardness. Mean hardness of discontinuous precipitation during aging increased with lower aging temperature and higher aluminum content. Furthermore, over-aged microstructure of Mg-Al system alloys differed from aluminum content or aging temperature.

Precipitate and Age Hardening Response of As-Cast Mg-8Yb-0.5Zr Magnesium Alloy

2011 ◽  
Vol 399-401 ◽  
pp. 17-20
Author(s):  
Wen Bin Yu ◽  
Zhi Qian Chen ◽  
Mang Zhang ◽  
Zhou Yu
Keyword(s):  
Heat Treatment ◽  
Magnesium Alloy ◽  
Grain Boundaries ◽  
Microstructure Evolution ◽  
Solution Heat Treatment ◽  
Artificial Aging ◽  
Precipitation Hardening ◽  
Intermetallic Phase ◽  
Age Hardening ◽  
Maximum Hardness

The precipitation hardening response of as-cast Mg-8Yb-0.5Zr magnesium alloy was investigated in the present work. The microstructure evolution of the alloy illustrated that Mg2Yb intermetallic phase was dissolved by solution heat treatment at 520°C for 12 hours. An apparent precipitation hardening response in Mg-8Yb-0.5Zr was discovered after artificial aging at 150°C, with maximum hardness increment of about 80 percent at the peak condition. It was found that the precipitates of the alloy were in the shape of two conjoined cosh and globe about 50 nm, and precipitated preferentially on grain boundaries and dislocations.

Effects of Erbium Addition on the Corrosion Resistance and Microstructure of AZ91 Magnesium Alloy

2011 ◽  
Vol 194-196 ◽  
pp. 1221-1224 ◽  
Author(s):  
Zhong Jun Wang ◽  
Yang Xu ◽  
Jing Zhu
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Discontinuous Precipitation ◽  
Az91 Magnesium Alloy ◽  
Continuous Precipitation ◽  
Az91 Magnesium ◽  
Precipitation Phase

The microstructures and corrosion resistance of AZ91 and AZ91+0.5 wt.% erbium (Er) magnesium alloys were studied, respectively. The results show that the Er addition in scrap AZ91 magnesium alloy can improve the corrosion resistance, markedly. The discontinuous precipitation phase (DPP) for Mg17Al12was retarded and the amount of DPP was decreased by 41% due to the formation of Al8ErMn4phase during solidification. The amount of continuous precipitation phase (CPP) in grains was decreased by 8% because of the formation of Al7ErMn5phase during solidification.

Microstructure and Aging Behavior in AM60 Magnesium Alloy Cast into Sand and Permanent Molds

2010 ◽  
Vol 654-656 ◽  
pp. 679-682 ◽  
Author(s):  
Hiroshi Yamada ◽  
Mitsuaki Furui ◽  
Susumu Ikeno ◽  
Yukio Sanpei ◽  
Katsuya Sakakibara ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Aging Temperature ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Age Hardening ◽  
Cellular Precipitation ◽  
Lower Aging Temperature ◽  
Peak Aging ◽  
Alloy Castings ◽  
Hardening Curve

AM60 magnesium alloy castings gave the solution treatment at 688K for 86.4ks. After that, aging treatment was carried out at three temperatures of 473, 498 and 523K. The age hardening curve obtained, hardness of all the specimens in the condition of peak aging was increased by decreasing the aging temperature. In the condition of long aging time, a cellular precipitation grows up from grain boundary to crystal grain. Fine cellular precipitation and intergranular precipitation obviously occurs at the lower aging temperature.

Effect of Aging Temperature on Microstructure and Mechanical Properties of AZ81-4%Gd Magnesium Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 301-306
Author(s):  
Quan Ying Guo ◽  
Zheng Liu ◽  
Ping Li Mao ◽  
Jing Sun
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Aging Temperature ◽  
Energy Dispersive Spectrometer ◽  
Alloy Sheet ◽  
Precipitation Pattern ◽  
Continuous Precipitation ◽  
Hardness Tester ◽  
Microstructure And Mechanical Properties ◽  
Alloy Hardness

The microstructure and mechanical properties of AZ81-4%Gd magnesium alloy sheet after aging at 150, 200, 250, 300 were analyzed and tested by x-ray diffraction,scanning electron microscope,energy dispersive spectrometer and hardness tester. The results demonstrated that β-Mg17Al12 phases were precipitated in two patterns, those were continuous precipitation and discontinuous precipitation during aging below 250 and the morphology of β-Mg17Al12 phase was different. The β-Mg17Al12 phases were precipitated in the pattern of continuous during aging at 300. The analysis showed that the precipitation pattern and morphology of β phases were related to the mechanism of nucleation and growth. The alloy hardness achieved the highest value after aging at 250 and 300 for 24 hours, the hardness of the alloy was the highest after aging at 150 and 200 for 32 hours. In addition, the observations on microstructure and the testing on hardness revealed that the best aging temperature is 200 for the AZ81-4%Gd alloys within the scope of the study.

scholarly journals Microstructure and age hardening behavior of AM60 magnesium alloy sand castings

2011 ◽  
Vol 61 (12) ◽  
pp. 699-704 ◽  
Author(s):  
Mitsuaki Furui ◽  
Yuhei Ebata ◽  
Susumu Ikeno ◽  
Katsuya Sakakibara ◽  
Seiji Saikawa
Keyword(s):  
Magnesium Alloy ◽  
Age Hardening ◽  
Hardening Behavior

Age Hardening Behavior of Al-Li Alloys Produced by Sand Mold Process

2016 ◽  
Vol 879 ◽  
pp. 1629-1633
Author(s):  
Seiji Saikawa ◽  
Chiharu Otsubo ◽  
Susumu Ikeno ◽  
Koichi Komai
Keyword(s):  
Mechanical Properties ◽  
Sand Mold ◽  
Age Hardening ◽  
Peak Hardness ◽  
Metal Mold ◽  
Hardening Behavior ◽  
Highly Active ◽  
Solution Treated ◽  
Mold Casting ◽  
Good Material

Al-Li alloys have higher mechanical properties and more lightweight than other conventional aluminum alloys. Therefore , it is focused as a good material for weight reduction of industrial fields. However, since the Al-Li alloy are highly active and hard to cast, there has been limited research on casting. In this study, age-hardening behavior of Al-2.5mass%Li alloys cast into sand and metal mold were investigated. All alloys cast into Y-block shape sand mold, and then artificial aged after solution treated at 743K for 36ks. Because of difference in quantity of precipitation by metastable δ’(Al3Li) phase, peak hardness of metal mold casting is higher than that of sand molds castings.

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