Ausforming treatment (deformation of austenite at temperature above Md) can improve the shape memory effect of Fe-MnSi based shape memory alloys, however, the mechanism of this improvement is not so clear. In this paper, the influence of ausforming treatment on stress-induced martensitic transformation and its reverse transformation in an Fe-28Mn-65i-5Cr (mass%) shape memory alloy has been studied using atomic force microscope (AFM) and TEM aiming to clarify the origin of this improvement. It was found that the ausforming treatment at 970K by 9% pre-straining, which is the optimum condition for improving shape memory recovery, can introduce many uniformly distributed stacking faults on the same slip plane in austenite. When an external stress is applied to such an ausformed specimen for shape change, uniformly distributed martensite bands with the same variant are produced in a grain due to the assistance of those preexisted stacking faults. When being heated over AS, these martensite bands are nearly completely reverse-transformed to parent phase through the same atomic pass as for the forward transformation, so a nearly perfect shape memory effect (over 90%) is obtained.
Reinforced concrete structures are easily corroded in the Salt Lake areas of China, especially in harsh environmental circumstance, such as freezing-thawing cycles, wetting-dry, et al, thus causing a lot of damage problems (concrete deterioration and steel bars corrosion). This research investigation was a research study which was to solve the corrosion problem of reinforced concrete structures under the chloride environmental circumstance through the electrochemical performance and mechanical properties test of the reinforced mortar specimens, the effect of single or compound doping of two organic and two inorganic corrosion inhibitors to the electrode potential, electrochemical impedance spectroscopy and mechanical properties of the reinforced mortar were investigated. The experimental conclusion demonstrated that the organic or inorganic corrosion inhibitors after single and compound doping showed some degree influence on the electrode potential and mechanical properties of the reinforced mortar specimens. Meanwhile, when the ratio of triethanolamine (TEA):triisopropanolamine (TIPA) was 7:3, sodium monofluorophosphate (MFP):sodium molybdate was 5:5, the compressive strength and flexural strength of mortar after curing for 28 days were greater than 90%, it indicated that these proportions showed the best corrosion resistance performance of steel bars. Therefore, these proportions of corrosion inhibitors could be used in reinforced concrete structures. The significant was that these results could provide theoretical guidance and technical basis for the study of corrosion damage of reinforced concrete structures in the future.
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