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Showing 1 to 20 of 21 for “"Age Hardening"”.
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Age-hardening of a copper-cobalt and a copper-iron alloy
Thesis: Sc. D., Massachusetts Institute of Technology, Department of Metallurgy, 1939
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A further study of the incubation period of the age-hardening of aluminum-copper alloys
Turnbull’s transient nucleation theory, when applied to the transformation that takes place when high purity aluminum-copper alloys are quenched directly to the aging temperature, explains the incubation period that precedes steady state nucleation. This incubation period arises from the …
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Development of Antioxidant Treatments for Asphalt Binders and Mixtures
… more effective antioxidants to control asphalt age-hardening, eight additives were evaluated based on their potential to reduce age-hardening in asphalts. The selected additives were used to modify a PG 64-22 asphalt binder in the laboratory. The modified binders were subjected to accelerated …
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High density bimodal parts by three dimensional printing
… exhibits good dimensional control (net shrinkage of 0.2%) and age-hardening properties (up to 43 HRC). The second system, a bimodal system of large Stainless Steel and fine TiC powders, is characterized by modest dimensional control (less than 2%), but does not exhibit any age-hardening …
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Structures and properties of lath martensite in rapidly solidified and conventionally processed iron-nickel-manganese-(titanium) maraging alloys
… processed Fe-Ni-Mn-(Ti) martensitic alloys aged at 400-550$\sp\circ$C up to 600 hrs have been studied. Upon aging from 400 to 550$\sp\circ$C, the alloys showed classical age-hardening behavior and the activation energies for precipitation were calculated as 24 Kcal/mole for Fe-Ni-Mn alloys …
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Ageing and strengthening of cold-rolled Al-Mg(-Cu)-Si-Mn alloys: experimental analysis and modelling
… the final strength of cold rolled alloys during ageing: solid solution, work hardening, recovery and precipitation. Microstructure analyses revealed the formation of undissolved particles consuming the small Si addition, which influences age hardening behaviour of the alloys. Tensile testing was …
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Impedance spectroscopy response of aluminum-copper-silicon alloys
… in both the solution-treated and artificially aged conditions. The solution-treatment procedure involved heating the alloys to 550$\sp\circ$C for 30 minutes and subsequently water-quenching. Artificial aging was carried out at 250$\sp\circ$C. Increased aging times of 1, 2, 8 and 32 hours at …
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Hydrogen embrittlement: an interfacial phenomenon
… interface degrades the mechanical properties. In age hardening experiments, hydrogen segregation caused an increase in the overaging kinetics in 2024 Al. This caused local softening of the aluminum and was probably due to the effect of hydrogen in promoting a loss of coherency at …
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Origins of Embrittlement of an Al-Zn-Mg-Cu Alloy Post Additive Friction Stir Deposition
… the as deposited and heat treated condition via age hardening studies and tensile testing. It is found that an embrittlement phenomena occurs that is sensitive to processing parameters and quench rate during heat treatment. Through the use of SEM, TEM, and APT the embrittlement phenomena has been …
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Development of an advanced materials system for tooling produced by three-dimensional printing
… 22Mn infiltrant. The Cu-Ni-Mn alloy is age hardenable. Acrysol was retained as the binder material again. Experiments were carried out to study the printing, debinding/sintering and infiltration steps. An extra age hardening step was also introduced after infiltration. The process …
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Characterization of aged polymer modified asphalt cements for recycling purposes
… wear on some of these pavements is reaching a stage where resurfacing is necessary. This research focuses on the characterization of aged polymer modified asphalt cements (PMAC) to evaluate their potential for recycling. A styrene-butadiene-styrene tri-block (SBS) polymer modified asphalt cement …
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The role of interstitial nitrogen in the precipitation hardening reactions in high-chromium ferritic steels
… - 0,04% nitrogen were found to constitute an age hardening system when quenched from a temperature of nitrogen solubility and exposed at temperatures in the range 600 - 700°C. TEM observations on thin foils revealed that hardening was associated with the formation of a high density of Cr-N …
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X-ray diffraction study of aged copper beryllium alloys
… structures in the process of aging and the age hardening mechanism of the alloy. The diffraction profiles from samples aged for different times at 315°C are collected using a position sensitive proportional counter with eu 1(0:1 radiation. The hardness values of the samples are also …
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Rehardenable materials system with diffusion barrier for three-dimensional printing
… infiltrated with Cu-20Ni-20Mn infiltrant. Age hardening at 450° C for one day resulted in a high macrohardness of 40 HRC, surpassing the current 3DP metal system for injection molding tooling. Future works on the study of other diffusion barrier materials and fluidized-bed CVD for metal …
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Composition and microstructure evolution in semi-solid cast Al-Zn alloys
… to derive optimum strength during subsequent ageing treatments. If the semi-solid metal castings can be age hardened to the same extent as the equivalent wrought competition, then this process could replace the machining of parts from conventional wrought stock. The semi-solid cast …
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Designing Microstructure through Reverse Peritectoid Phase Transformation in Ni₃Mo Alloy
… Supersaturated solid solution samples were first aged at 600C for 100h followed by quenching to form the equilibrium γ-Ni₃Mo phase. After that, the samples were heat treated between 910°C and 1050°C for up to 10h followed by quenching. Regardless of heat-treatment temperature, samples heat-treated …
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Strength modelling of Al-Cu-Mg Type alloys
Age hardening of Al-Cu-Mg type alloys occurs in two stages separated by a constant hardness plateau when the alloys are aged at 110°C to 240?C after solution treatment and quenching. This work aims to develop a physically based two-stage hardening model to predict the yield strength of Al-Cu-Mg …
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Understanding the role of calcium on the reaction mechanism of geopolymer cements through addition of nucleation seeds
… of C-S-H/C-A-S-H is known to initiate the rapid hardening which then is hypothesized to act as a nucleation site for the precipitation of aluminosilicate gel. This study verified the hypothesis through the addition of synthesized C-S-H/C-A-S-H as an external seed during the processing of …
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Development of a New High Performance Cold Mix Asphalt
… years, global climate change and energy shortages have become serious issues of common concern internationally. The majority of roads and highways are paved using hot mix asphalt (HMA) technology. The manufacture of hot mix asphalt is a key source of energy consumption, greenhouse gas …
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Microstructural evolution and mechanical behavior in nickel based alloys for very high temperature reactor
… independent as a result of additional strain hardening provided by dynamic strain aging. However, higher temperatures (>800ºC) activated additional deformation mechanisms, including dislocation creep and dynamic recrystallization, leading to a significant decrease in material strength. …
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