The microstructures of as-extruded and stabilizing heat-treated Zn-10Al-2Cu-0.02Ti alloys were observed by scanning electron microscopy,transmission electron microscopy,electron probe microanalysis and X-ray diffracti...The microstructures of as-extruded and stabilizing heat-treated Zn-10Al-2Cu-0.02Ti alloys were observed by scanning electron microscopy,transmission electron microscopy,electron probe microanalysis and X-ray diffraction analysis techniques.The change in structure after heat treatment and its effects on room temperature creep behavior were investigated by creep experiments at constant stress and slow strain rate tensile tests.The results show that after stabilizing heat treatment（（350℃,30 min,water-cooling）＋（100℃,12 h,air-cooling））,the amount of α＋η lamellar structure decreases,while the amount of cellular and granular structure increases.The heat-treated Zn-10Al-2Cu-0.02Ti alloy exhibits better creep resistance than the as-extruded alloy,and the rate of steady state creep decreases by 96.9% after stabilizing heat treatment.展开更多
The effects of heat treatments on typical microstructures of directionally solidified（DS） Ti-45Al-8Nb-（W,B,Y）（molar fraction,%） alloys prepared by the Bridgeman method were studied.Two typical DS microstructures...The effects of heat treatments on typical microstructures of directionally solidified（DS） Ti-45Al-8Nb-（W,B,Y）（molar fraction,%） alloys prepared by the Bridgeman method were studied.Two typical DS microstructures including full lamellae with cellular growth morphology and massive structure with dendritic growth morphology were examined.The results show that the heat treatment of 1250 ℃ for 24 h ＋ 900 ℃ for 30 min＋air cooling can efficiently eliminate the B2 phase in the DS alloys and change the massive structure of the rapid DS alloy into lamellar microstructure.Columnar lamellar colonies with widths of 150-200 μm and 50-100 μm respectively were observed in intercellular and dendritic arm regions.The heat treatment of 1 400 ℃ for 12 h＋900 ℃ for 30 min＋air cooling could simultaneously remove the B2 phase,massive structure and solidification segregations from the DS alloys,however,it caused severe growth of grains.展开更多
Effects of Al content and heat treatment on the structure,hardness and electrochemical properties of FeCoNiCrCu0.5Alx high-entropy alloys were investigated.The phase structure of as-cast alloys evolves from FCC phase ...Effects of Al content and heat treatment on the structure,hardness and electrochemical properties of FeCoNiCrCu0.5Alx high-entropy alloys were investigated.The phase structure of as-cast alloys evolves from FCC phase to BCC phase with the increase of Al content.The stable phase of FeCoNiCrCu0.5Alx high-entropy alloys will transform from FCC phase to FCC＋BCC duplex phases when x value increases from 0.5 to 1.5.The hardness of BCC phase is higher than that of FCC phase,and the corrosion resistance of BCC phase is better than FCC phase in chlorine ion and acid medium.High hardness and good corrosion resistance can be obtained in as-cast FeCoNiCrCu0.5Al1.0 alloy.展开更多
基金Project(2009BAE71B00) supported by the National Key Technology R&D Program during the Eleventh Five-Year Plan Period
文摘The microstructures of as-extruded and stabilizing heat-treated Zn-10Al-2Cu-0.02Ti alloys were observed by scanning electron microscopy,transmission electron microscopy,electron probe microanalysis and X-ray diffraction analysis techniques.The change in structure after heat treatment and its effects on room temperature creep behavior were investigated by creep experiments at constant stress and slow strain rate tensile tests.The results show that after stabilizing heat treatment（（350℃,30 min,water-cooling）＋（100℃,12 h,air-cooling））,the amount of α＋η lamellar structure decreases,while the amount of cellular and granular structure increases.The heat-treated Zn-10Al-2Cu-0.02Ti alloy exhibits better creep resistance than the as-extruded alloy,and the rate of steady state creep decreases by 96.9% after stabilizing heat treatment.
基金Projects(50771013,50871127)supported by the National Natural Science Foundation of China
文摘The effects of heat treatments on typical microstructures of directionally solidified（DS） Ti-45Al-8Nb-（W,B,Y）（molar fraction,%） alloys prepared by the Bridgeman method were studied.Two typical DS microstructures including full lamellae with cellular growth morphology and massive structure with dendritic growth morphology were examined.The results show that the heat treatment of 1250 ℃ for 24 h ＋ 900 ℃ for 30 min＋air cooling can efficiently eliminate the B2 phase in the DS alloys and change the massive structure of the rapid DS alloy into lamellar microstructure.Columnar lamellar colonies with widths of 150-200 μm and 50-100 μm respectively were observed in intercellular and dendritic arm regions.The heat treatment of 1 400 ℃ for 12 h＋900 ℃ for 30 min＋air cooling could simultaneously remove the B2 phase,massive structure and solidification segregations from the DS alloys,however,it caused severe growth of grains.
基金Project(NCET-11-0127) supported by the Program for New Century Excellent Talents in University,ChinaProject supported by the Fundamental Research Funds for the Central Universities,China
文摘Effects of Al content and heat treatment on the structure,hardness and electrochemical properties of FeCoNiCrCu0.5Alx high-entropy alloys were investigated.The phase structure of as-cast alloys evolves from FCC phase to BCC phase with the increase of Al content.The stable phase of FeCoNiCrCu0.5Alx high-entropy alloys will transform from FCC phase to FCC＋BCC duplex phases when x value increases from 0.5 to 1.5.The hardness of BCC phase is higher than that of FCC phase,and the corrosion resistance of BCC phase is better than FCC phase in chlorine ion and acid medium.High hardness and good corrosion resistance can be obtained in as-cast FeCoNiCrCu0.5Al1.0 alloy.
