Lattice Defects Affecting Moisture-Induced Embrittlement of Ni-based L12 Ordered Intermetallics

1996 ◽  
Vol 460 ◽  
Author(s):  
T. Takasugi ◽  
S. Hanada
Keyword(s):  
Heat Treatment ◽  
Tensile Test ◽  
Grain Boundaries ◽  
Tensile Ductility ◽  
Lattice Defects ◽  
The Other ◽  
Treatment Conditions ◽  
Deformation And Heat Treatment ◽  
Test Atmosphere ◽  
Kinetics Of

ABSTRACTMoisture-induced embrittlement of Ll2 alloys (such as Ni3(Si,Ti) and Ni3AI) is observed by tensile test and SEM fractography. A variety of microstructures were prepared by selecting pre-deformation and heat treatment conditions. It is shown that tensile ductility and the associated fractography depend on structure as well as test atmosphere. Well-annealed specimens are susceptible to moisture-induced embrittlement while pre-deformed specimens are resistive to moisture-induced embrittlement. Also, this embrittlement is generally sensitive to the heat treatment scheme preceded by the pre-deformation. Results indicate that the embrittlement occurs when hydrogen is enriched on grain boundaries. On the other hand, the embrittlement can be suppressed when hydrogen is trapped at lattice defects such as dislocations and vacancies. These results are discussed in association with the kinetics of hydrogen in the pre-deformed microstructure.

Creep Behavior and Microstructures in Grain Boundary Strengthened Mg-Al-Ca Thixomolded® Alloys

2012 ◽  
Vol 706-709 ◽  
pp. 1249-1254
Author(s):  
Mayumi Suzuki ◽  
Akihiro Shibata ◽  
Kouichi Maruyama
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Creep Strength ◽  
Small Addition ◽  
The Other ◽  
Number Density ◽  
Misch Metal ◽  
Microstructure Stability ◽  
Treatment Conditions

The microstructures of thixomolded® (TM) Mg-Al-Ca alloys consist of α-Mg and eutectic compounds along grain boundaries. Misch metal (Mm) addition to TM Mg-Al-Ca alloys makes precipitates within α-Mg matrix and their number density and size depend on heat-treatment conditions. The small addition of Mm can keep the network-like grain boundary covering and the improvement of microstructure stability during creep. On the other hand, excessive Mm addition causes the deterioration of creep strength. The grain boundary coverage decreases with increasing Mm content due to the formation of coarse spherical Al-Mm based intermetallic compounds. Creep strength is significantly affected by both of the grain boundary coverage and the morphology of eutectic compounds along grain boundaries.

Effect of Heat Treatment Conditions and Small Addition of Cu on Occurrence of Serration in Al-Si Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 180-185
Author(s):  
Teruto Kanadani ◽  
Norihito Nagata ◽  
Keiyu Nakagawa ◽  
Koji Murakami ◽  
Makoto Hino
Keyword(s):  
Heat Treatment ◽  
Binary Alloy ◽  
Room Temperature ◽  
Small Addition ◽  
The Other ◽  
Aging Rate ◽  
Aging Period ◽  
Treatment Conditions ◽  
Heat Treated ◽  
Aging Conditions

In this study, the effect of heat treatment conditions and small addition of Cu on occurrence of serration in Al-Si alloys was investigated. Specimens were aged for various times up to 87ks at 273K or 473K after quenching from 853K, and tensile-tested at room temperature. In the binary alloy, serration was observed even after aging for 87ks at 273K, while in the case of aging at 473K, serration did not occur under aging conditions at aging time, tA≧20s. On the other hand, serration was observed even after aging for 72ks at 473K in the Cu-added alloy. In both alloys, serration was also recognized when the specimens were furnace-cooled from 853K to room temperature. Thus, for aging at 473K of the binary alloy serration was observed only when the aging period was short enough, but addition of Cu to the binary alloy prolonged the aging period where serration could be recognized. Aging rate of both alloys measured by tensile strength was almost the same. The size of precipitates in the Cu-added alloy was smaller than that in binary alloy. Moreover, the number of the precipitates at the grain boundary in the Cu-added alloy was smaller than that in the binary alloy. It is considered that serration occurs for Al-Si alloys when the specimen is heat-treated so that small precipitates may be formed. Now the details of the effect of Cu addition are not clear.

scholarly journals Effect of heat treatment on the microstructure and mechanical properties of a low-carbon X80 pipeline steel

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
B.C. Acosta-Cinciri ◽  
N.M. López-Granados ◽  
J.A. Ramos-Banderas ◽  
C.A. Hernández-Bocanegra ◽  
P. Garnica-González ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Pipeline Steel ◽  
American Petroleum Institute ◽  
The Other ◽  
Low Carbon ◽  
Electron Backscattered Diffraction ◽  
X80 Pipeline Steel ◽  
Microstructure And Mechanical Properties ◽  
Treatment Conditions

Abstract In this work, the effect of heat treatment conditions on the microstructure and mechanical properties of an American Petroleum Institute (API) X80 steel with a low carbon content of ~0.02% wt., destined for the manufacture of pipelines and pipeline transmission systems by welding, was investigated. Samples were heat treated under different conditions and then were characterized by scanning electron microscopy (SEM), orientation image microscopy (OIM), and electron backscattered diffraction (EBSD). The results showed that when the steel is fastly cooled from the austenitic field (990°C), the mechanical properties increase significantly [ultimate tensile strength (UTS) >1,100 MPa, yield strength (YS) 900 MPa, and elongation 27%] due to the high percentage of martensite (M) present in the microstructure (95%). In contrast, when the cooling rate decreases and the treatment conditions remain at/or above the bainitic/martensitic transformation (from 990°C to 600°C and 450°C), the mechanical properties are decreased by almost 50% because of the decrease in the percentage of martensite (18%). However, the percentage of elongation increases significantly (38%) due to the presence of other micro-constituents resulting from the phase transformation. On the other hand, the best combination of mechanical properties (UTS above 800 MPa and YS between 610 MPa and 720 MPa) was obtained when the steel acquired a dual-phase microstructure [(martensite/austenite)-(ferrite/martensite)] since the amount of martensite is conserved between 45% and 82%, in combination with the other micro-constituent present in the steel that allows us to achieve elongation percentages close to 30%.

Effect of Heat Treatment Conditions on Microstructures and Mechanical Properties of Cu-9Ni-6Sn-0.22Nb Alloy

2021 ◽  
Vol 904 ◽  
pp. 124-130
Author(s):  
Si Yang Xu ◽  
Ying Long Li ◽  
Mu Xin Zhang ◽  
Yi Fu Jiang ◽  
Hua Ding
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Electrical Conductivity ◽  
Grain Boundaries ◽  
Spinodal Decomposition ◽  
Ageing Time ◽  
High Strength ◽  
Ageing Temperature ◽  
Treatment Conditions ◽  
The Matrix

Due to its high strength, excellent electrical conductivity and high resistance to stress corrosion, Cu-Ni-Sn alloy has been selected as a kind of advanced metal material which can be used as the manufacture of springs, connectors, bearings and so on. In addition, the addition of Nb can efficiently improve the comprehensive properties of the alloy. In the present work, the effect of heat treatment conditions on microstructure and mechanical properties were studied in a Cu-9Ni-6Sn-0.22Nb alloy by means of optical microscopy (OM), transmission electron microscopy (TEM), tensile test and microhardness tests. The results show that before ageing, a large number of fine γ precipitates with DO22 type structure are distributed on the matrix. With the prolongation of ageing time, the ultimate tensile strength (UTS), yield strength (YS) and Vickers hardness increased firstly, and then decline. The reason can be attributed to the occurrence of spinodal decomposition and the formation of discontinuous precipitation (DP). At first, spinodal decomposition induced the enhanced interaction between dislocations and internal stress field, resulting in an increase of mechanical properties. Then the increased DP at grain boundaries leads to the decline of strength in the material. Finally, the relationship between the microstructure and the electrical conductivity was also analyzed, and the results show that the electrical conductivity increased with ageing time/ageing temperature increasing for the present alloy. Through the analysis of Matthiessen’ s rule, the variation of electrical resistivity depends on precipitates, solute atoms, dislocations, vacancies and grain boundaries, and the precipitates play an important role among them. Besides, more precipitates improve electrical conductivity. Therefore, the increase of ageing time/ageing temperature induced the increase of DP, resulting in an increase of electrical conductivity.

Study of the Artificial Aging Kinetics of Different AA6013-T4 Heat Treatment Conditions

2011 ◽  
pp. 321-328 ◽  
Author(s):  
Josef Berneder ◽  
Ramona Prillhofer ◽  
Josef Enser ◽  
Peter Schulz ◽  
Carsten Melzer
Keyword(s):  
Heat Treatment ◽  
Artificial Aging ◽  
Treatment Conditions ◽  
Aging Kinetics ◽  
Kinetics Of

Effects of Heat Treatment Conditions on Fresh Taste and on Pectinmethylesterase Activity of Chilled Mandarin and Orange Juices

2005 ◽  
Vol 11 (3) ◽  
pp. 217-222 ◽  
Author(s):  
E. Sentandreu ◽  
L. Carbonell ◽  
J. V. Carbonell ◽  
L. Izquierdo
Keyword(s):  
Heat Treatment ◽  
Enzyme Activity ◽  
Retention Time ◽  
Residual Activity ◽  
The Other ◽  
Residual Enzyme Activity ◽  
Drastic Reduction ◽  
High Quality ◽  
Treatment Conditions ◽  
Mandarin Juices

Juices from oranges, mandarins and hybrids were thermally treated in a plate exchanger at different conditions to evaluate the effects of treatment on fresh taste and on residual pectinmethylesterase (PME) activity. Freshness was significantly higher in fresh juices than in samples treated at 70°C or higher temperatures for 10 seconds of retention time, whereas no differences were found among samples heated at temperatures from 70 to 90°C for the same time, however at 95°C fresh taste decreased again. Residual PME activity was about 20% in samples treated at 70°C for 5, 10 and 20 seconds and in those heated at 80°C for 5 and 10 seconds, decreasing to 15%, also at 80°C, when retention time increased to 20 seconds. A drastic reduction to about 3% of residual activity was observed at 85°C for 10 seconds. Minimum activities of 0-1% corresponded to samples treated at 95°C. Considering the results of sensory and residual enzyme analyses, the treatment at 85°C for 10 seconds can be considered suitable. In these conditions fresh taste did not differ from that of juices treated at lower temperatures but residual enzyme activity was clearly smaller and acceptable for chilled juices, products of high quality but short shelf life. On the other hand, a deeper reduction of PME activity increasing the temperature to 95°C does not seem advisable since fresh taste decreases. Mandarin juices pasteurised at 85°C for 10 seconds and pasteurised again at the same conditions did not show a further decrease of fresh taste. Two heat treatments were usually applied when packing plants receive the juice from other factories.

Effect of Heat Treatment Temperature on the Mechanical Property in Cast TiNi Shape Memory Alloy

2007 ◽  
Vol 561-565 ◽  
pp. 1493-1496
Author(s):  
Kazuhiro Kitamura ◽  
Yutaka Sawada ◽  
Toshio Kuchida ◽  
Tadashi Inaba ◽  
Masataka Tokuda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Shape Memory Alloy ◽  
Tensile Test ◽  
Shape Memory ◽  
Treatment Temperature ◽  
Scanning Calorimetry ◽  
Temperature Synthesis ◽  
Treatment Conditions ◽  
High Temperature Synthesis

The heat treatment effect of a cast shape memory alloy (SMA) from self-propagating high temperature synthesis (SHS) ingot was investigated. The composition of SHS ingot was Ti-50.8at%Ni. DSC and Tensile test specimens were cast by lost-wax process from SHS ingot. The heat treatment conditions were 400°C-60min., 500°C-60min. and 600°C-60min. for DSC and 400°C-60min. and 500°C-60min. for tensile test. Transformation temperatures were measured by differential scanning calorimetry (DSC). Mechanical properties were measured by a tensile test at several temperatures. The effects of heat treatment temperatures were same as a general TiNi wire material.

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