Effect Of Room Temperature Aging Research Articles

Effects of Room Temperature Aging on Adhesion of Electroless Plating Film on Silicon Using Gold Nanoparticle Catalysts

Effects of Room Temperature Aging on Adhesion of Electroless Plating Film on Silicon Using Gold Nanoparticle Catalysts

Microscopic characterization of structural relaxation and cryogenic rejuvenation in metallic glasses

Plasticity improvement in metallic glasses resulting from cycling treatment between room and liquid nitrogen temperature has been reported and attributed to rejuvenation due to a non-uniform thermal expansion coefficient. However, the detailed microscopic effect is still unclear. The present study focuses on the microscopic effect of room-temperature ageing and cryogenic cycling. La70Cu15Al15 and La70Ni15Al15 metallic glasses were subjected to varying ageing times, after which some were also cryogenically cycled. Quasi-static anelastic relaxation measurements were then employed to characterize the time-constant spectra over seven orders of magnitude. The overall anelastic strain decreases with increasing ageing time, but is not noticeably affected by cryogenic cycling. On the other hand, while ageing also causes an increase in characteristic time constants, cycling reverses this effect. The new details shed light on the effect of structural relaxation and rejuvenation on the properties of shear transformation zones.

Effect of room temperature ageing on structure and thermal stability of as-cast and deformed Pd40Ni40P20 metallic glass

The effect of long-term room temperature ageing on structure and thermal stability of as-cast and inhomogeneously deformed Pd[Formula: see text]Ni[Formula: see text]P[Formula: see text] metallic glass has been investigated. It is found that the first crystallization peak temperature decreases and this indicates that the thermal stability decreases after ageing for these as-cast and inhomogeneously deformed metallic glass samples. The high density of shear bands formed after deformation disappears and nanocrystallization has been observed after ageing for the inhomogeneously deformed Pd[Formula: see text]Ni[Formula: see text]P[Formula: see text] metallic glass.

(Invited) Room Temperature Aging Effect Improvement for Device Stability and Manufacturability of FinFET Technologies

In CMOS manufacturing industry, device threshold voltage (Vt) stability is a pre-requisite for volume manufacturing. Device architectural elements, process parameters and room temperature aging (Q-time) are the main source of Vt instability. In FinFET technology with metal/high-K gate, device Vt is controlled through effective work function engineering by optimal metal layer thickness as well as controlled Aluminum (Al) doping/diffusion within the gate stack [1-4]. The device Vtcan also be influenced by its architectural elements and process parameters [5] which should be well controlled during the volume manufacturing. However, room-temperature Q-time effects at several stages of the manufacturing process are practically unavoidable. This work demonstrates post n-work function (WF) deposition Q-time impact on device Vt instability. Longer Q-time induced Vt shifts that are independent of gate length and number of fins, as seen in Figure 1. The root cause investigations were performed using device characterization followed by elemental analysis of the gate stack (Figure 2). It was found that, the content of oxygen (O2) and Al in the gate stack is well correlated to post n-WF deposition Q-time. The device Vt instability can be explained by oxygen incorporation due to n-WF layer oxidation during the Q-time post n-WF deposition and the corresponding reduction of Al diffusion into the high-K capping layer [2, 6]. In this work, n-WF layer thickness/composition was optimized to enable immunity to a larger Q-time limit for volume manufacturing, as demonstrated in Figure 3 from n-WF layer recipe group A to group C. The reliability impact of the gate stack was also assessed. Device benefits such as Tinv scaling and thereby Ion-Ioffperformance improvement was also demonstrated without compromising the reliability. Reference [1] L.P.B. Lima et al, J. Appl. Phys., 115, 074504, 2014 [2] A. Veloso et al, Jpn. J. Appl. Phys.52. 04CA02, 2013 [3] L. Kornblum et al, Appl. Phys. Lett., 100, 062907, 2012 [4] C.L. Hinkle et al, Appl. Phys. Lett.,96, 103502, 2010 [5] M. Togo et al, VLSI tech. Symp. Dig.pp. 140-141, 2014 [6] A. Veloso et al, VLSI Tech. Symp. Dig. pp. 34-35, 2011. Figure 1

(Invited) Room Temperature Aging Effect Improvement for Device Stability and Manufacturability of FinFET Technologies

In FinFET technology, device threshold voltage (Vt) stability is a pre-requisite for volume manufacturing. Device architectural elements, process parameters and room temperature aging (Q-time) are the main source of Vt instability. For the first time, we report a method to minimize Vt instability due to Q-time in gate stack work function (n-WF) layer film depositions. Underlying mechanism was investigated using elemental analysis. The optimized n-WF layer recipes were developed that are less sensitive to the Q-time. Device benefits such as Tinv scaling and thereby Ion-Ioff performance improvement is demonstrated without compromising the reliability.

Thermal cycling induced room temperature aging effect in Ni-rich NiTi shape memory alloy

This work shows that the characteristics of B19′ martensite transformation in Ni-rich NiTi alloys are rather stable during aging at room temperature after quenching from 1273K. However, if transformation cycles between austenite and martensite are performed, the B19′ martensite transformation can be strongly suppressed following aging at room temperature. As the NiTi elements normally experience cyclic transformation in applications, this phenomenon has to be taken into account as a factor for the functional degradation of NiTi alloys. Possible mechanisms of the uncovered aging effect are discussed.

On the effect of room temperature ageing of Ni-rich Ni–Ti alloys

We show that the cubic–monoclinic martensitic transformation (B2-B19′) in Ni-rich Ni–Ti alloys is strongly affected by room temperature exposure after quenching from 1270 K, presumably due to the initial stage of precipitation: transformation temperatures strongly decrease, the hysteresis increases and in the Ni50.8Ti49.2 alloy the transformation gets arrested. The suppression of the B2–B19′ transformation is not preceded by the cubic–trigonal (R-phase) transition, indicating that nm-size precipitates or their nuclei do not serve as nucleation sites for the R-phase.

Effect of room-temperature aging on shape memory characteristics of Ti–10Nb–10Zr–11Ta (at.%) alloy

In this study, the effect of room-temperature (RT) aging on the shape memory characteristics of the Ti–10Nb–10Zr–11Ta (at.%) alloy was investigated by tensile tests. Ingots were prepared using the arc melting method and then cold-rolled at a reduction of up to 95%. After cold-rolling, the plates were solution-treated at 1173K for 1.8ks, followed by aging at RT and temperatures up to ∼573K for various periods of times. Superior superelasticity was observed at RT in the solution-treated specimen. The critical stress for inducing martensitic transformation (σSIM), tensile strength, and critical stress for slip (σS) of specimens aged at RT increased with increasing aging time up to 60 days, showing no noticeable changes with further increases in the aging time. On the other hand, in the specimens aged at 373K, 423K, and 473K for 3.6ks, the values of σSIM and the tensile strength increased with increasing aging temperature, while the specimen aged at 573K exhibited mature fractures. There were little change in σSIM and σS of the specimen that was solution-treated followed by aging at 373K for 3.6ks during RT aging. This result indicated that aging at 373K resulted in good resistance against the effect of RT aging.

Influence of Additives and the Effect of Aging in Modifying Surface Topography of Electrodeposited Copper

The influence of most common additives used for copper electrodeposition on the physical, microstructure as well as the morphological character of the deposit has been studied. The effect of room-temperature aging on the microstructure of the copper deposit is also discussed in the present work. The X-ray diffraction pattern of the copper deposit has a prominent (111) orientation in addition to (200), (220), and (311) planes typical of copper deposits; the intensity of the planes during aging has a prominent (200) plane; and the ratio of to changes significantly. The scanning electron microscopy analysis showed that the deposit normally appears to have round or globular features and that there is a change in grain size with respect to a particular additive. From the atomic force microscopy analysis, we can confirm that the average grain size and the roughness of the copper deposits strongly depend on the deposition rate and the type of additive in the bath. There is a change in the grain size and the morphology of the copper deposit due to room-temperature aging. The roughness of the surface increases, and an abrupt shift in the hardness of the coating occurs during aging.

Effects of various pre-treatments and cold rolling on room temperature aging of 6000 series aluminum alloys

Three commercial age-hardenable alloys, 6022, 6063, 6N01, were cold rolled: CR at room temperature after the three different pre-treatments, which are solution treatment and iced water quenching: STQ, aging at room temperature for 864 ks after the STQ: RTA-1 and furnace cooling after holding at 623 K for 3.6 ks: O. These specimens were aged at room temperature for longer than 864 ks after the CR (RTA-2). Change in resistivity ρ at 77 K was traced from immediately after the CR to investigate work hardening and aging behavior at room temperature after CR. Vickers hardness HV was also measured 0.6 to 0.9 ks later from the STQ or CR. Increments in ρ and HV by the CR in the O state were smallest among the other pre-treatments. The CR in the STQ or RTA-1 state gave nearly same increments in ρ and HV. By the CR in the STQ state, aging rate of the RTA-2 was decreased with increasing true rolling strain. It is considered that this suppression of the RTA-2 may be attributed to “sweep out” of excess quenched-in vacancies by moving dislocations. This effect is expected to decrease the negative effect of room temperature aging on artificial age-hardening through decrease in amount of formed clusters by T3 treatments. In the final room temperature aging, RTA-2, after the RTA-1 and CR, initial aging rate was increased with true rolling strain. This observation suggests that vacancies were surely introduced by the CR. However, the acceleration of the RTA-2 was limited only short period till the excess vacancies annihilated to dislocations, which density was increased by the CR.

Effects of storage aging on the cure kinetics of T700/BMI prepregs for advanced composites

AbstractThe effects of room temperature aging on the cure kinetics of a bismaleimide (BMI) matrix prepreg have been characterized by different time and storage conditions. The study has focused on the stability of BMI matrix carbon fiber prepregs, when exposed to controlled environmental conditions before being used in composite manufacturing. The effects of aging on reactivity, glass transition temperature, and process window have been investigated by differential scanning calorimetrer through dynamic and isothermal tests. A theoretical kinetic model for epoxy matrix prepregs, developed in previous studies, has been applied to the cure of both aged and virgin BMI matrix. The model is able to satisfactorily describe the effect of processing variables such as temperature and degree of cure during the curing of the composite under different conditions (curing temperature and heating rate). The effects of diffusion‐controlled phenomena on the cure kinetics, associated with changes in glass transition temperature as a function of the degree of cure, have been taken into account in the formulation of an nth‐order kinetic model. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers

The effects of room temperature aging upon the magnetic properties of Ba-hexaferrite films grown on 6H-SiC substrates

The successes of making acceptable magnetic properties BaM films by different techniques based on pulsed laser deposition were reported in the past years. The key was to introduce a proper buffer layer to promote two dimensional growths on these semiconductor material substrates. After years, we go back to characterize these samples made by different processings. The purpose of this experiment is to explore the role of the buffer layers especially with the time dependence and thus demonstrate our film suitable for the potential future application. These samples are characterized by scanning electron microscopy, x-ray diffraction, and vibrating sample magnetometry comparing to characteristics of the as deposited films.

Aging phenomena in high-Si steels studied by internal friction

Si-steels with various Si-contents (1.9–5.6 wt.%) have been analyzed by internal friction and compared with an ultra-low carbon steel. Measurements have been carried out immediately after different thermomechanical treatments to study a believed aging phenomenon. Adding Si lowers the Snoek peak of carbon and produces a new peak associated to the formation of Si–C pairs. For Si contents higher than 4.6 wt.%, another peak appears at very low frequencies, which can be attributed to a Zener relaxation of Si-atom pairs. A room-temperature aging effect has been detected in the Si-steels, but not in the ultra-low carbon steel. This aging is caused by the migration of C atoms to the structural defects and by formation of short-range order in the Fe–Si solution.

Embrittlement in a bulk nanocrystalline alloy induced by room-temperature aging

The effect of room-temperature aging on the mechanical behaviors of an electrodeposited bulk nanocrystalline (nc) Ni–Fe alloy has been investigated. The tensile elongation to failure, εf, of the bulk nc Ni–Fe alloy decreased from approximately 7.2% in the as-deposited state to 5.0%, after aging at room temperature for one year. Moreover, the fatigue-endurance limit decreased from about 260to190MPa. This aging-induced embrittlement may be mainly due to the enhanced atomic diffusivity in the nc materials, leading to the segregation of the impurity atoms at the grain boundaries.

Effects of storage aging on the cure kinetics of bismaleimide prepregs

AbstractThe effects of room temperature aging on the subsequent polymerization kinetics of a bismaleimide (BMI) matrix prepreg, for high performance composites, have been characterized by different time and storage conditions. The study has focused on the stability of BMI matrix carbon fiber prepregs, when exposed to controlled environmental conditions before being used in composite manufacturing. The effects of aging on glass transition temperature, reactivity, and processability have been investigated by calorimetry through dynamic, isothermal, and cure‐simulating tests. A theoretical kinetic model for epoxy matrix prepregs, developed in previous studies, has been applied to the polymerization of both aged and unaged BMI matrix. The model is able to satisfactorily describe the effect of processing variables such as temperature and degree of reaction during the curing of the composite under different conditions (curing temperature and heating rate). The effects of diffusion‐controlled phenomena on the reaction kinetics, associated with changes in glass transition temperature as a function of the degree of polymerization and cross‐linking, have been taken into account in the formulation of an nth‐order kinetic model. © 2005 Wiley Periodicals, Inc. Adv Polym Techn 24: 253–265, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20048

Rapid synthesis of silicalite-1 nanocrystals by conventional heating

The effect of room temperature aging on the crystallization rate and size of MFI-type crystals synthesized under high temperature was investigated. First, synthesis mixtures yielding MFI-type zeolite were aged at room temperature for periods of time between 1 and 60 days. This was followed by a rapid synthesis in a pre-heated at 230 °C conventional oven. The utilization of a pre-aged initial systems and high heating rates allowed very rapid synthesis of zeolite. The effect of aging time, crystallization temperature, duration of synthesis and aluminum content on the crystal size and yield was systematically studied. Zeolite nanoparticles with sizes ranging from 130 to 260 nm and relatively narrow particle size distributions were synthesized employing the pure-silica system. The obtained nanocrystals were characterized by X-ray diffraction, scanning electron microscopy, dynamic light scattering and N 2 adsorption measurements.

Effect of aging on the rubber-like behavior in Cu-Zn-Al martensites

Martensites in several shape memory alloys exhibit peculiar pseudoelastic behavior, referred to as twinning pseudoelasticity or rubber-like behavior. By loading a sample in the martensite state, internal twin boundaries, or intervariant boundaries, move so as to increase the volume fraction of variants more favorable oriented to relieve the applied stress. On unloading, those boundaries tend to return to their original positions; accordingly, the sample restores it original shape. It has been recognized that the rubber effect appears only in aged martensites. When a martensite is deformed immediately after its formation, the boundary motion is not reversible; imposed strain remains after unloading. Unlike the case of superelasticity, which is another class of pseudoelastic behavior in shape memory alloys, the rubber effects does not involve any phase transformation. Deformation is undertaken merely by the reorientation of variants of a single martensite phase. While the free energy difference between two participant phases gives rise to the restoring force in superelasticity, there is, apparently, no such counterpart in the rubber-like behavior. The original of the restoring force in the rubber effect has long been a subject of controversy. In the present study, the authors have investigated the effects of room temperature aging on themore » stress-strain behavior quantitatively in both 9R and 18R martensites of Cu-Zn-Al alloys. In addition, changes in the reverse transformation temperature by aging have been measured. Since aging is known to significantly affect the reverse transformation behavior as well, they have intended to examine a correlation between the rubber-like behavior and the stabilization of martensites.« less

Compositional variations of porous silicon layers prior to and during ion-beam analyses

The suitability of ion-beam-analysis techniques in quantifying the composition of mesoporous silicon nanostructures has been critically examined using films of moderate porosity (55%) prepared on n+ substrates. The effects of room-temperature aging of as-etched and thermally oxidized porous silicon, the oxidation conditions chosen to render the material luminescent, have been carefully monitored, as have the effects of both ion-beam irradiation and storage of samples in vacuo. It is shown that the concentrations of the three major impurities oxygen, carbon, and hydrogen can be appreciably altered during analyses, thereby limiting the reliability of the techniques, as conventionally applied to porous silicon. The use of appropriate capping layers, which should alleviate the problem, is recommended.

A physicochemical study of the againg of colloidal silica gels used in zeolite Y synthesis

An investigation was carried out to determine the effects of room-temperature aging on the structure and composition of NaY zelite synthesis gels prepared from colloidal silica. Alkaline solutions containing varying amounts of sodium aluminate were added to a colloidal silica sol to produce gels of composition 4 Na 2O, x Al 2O 3, 10 SiO 2, 180 H 2O ( x = 0.0 –1.5). Each of the gels was homogenized and then allowed to age at room temperature. Changes in the composition and structure of the solid and liquid phases of zeolite synthesis gels were followed as a function of time using elemental analysis; n.m.r., i.r. and Raman spectroscopies; and X-ray diffraction. Initial mixing of the colloidal silica, caustic, and aluminate has no noticeable chemical or structural effects beyond gelation via flocculation of the silica particles and adsorption of AI and Na onto the surface of the particles. The colloidal silica dissolves during aging as a consequence of successive cleavage of siloxane bonds. Adsorption of AI reduces the rate of silica dissolution. The slow dissolution of the silica releases monomeric silicate anions that rapidly react with aluminate anions to form an aluminosilicate precipitate, estimated to have a Si Ai ratio of 1. Once the dissolved aluminum is depleted from the liquid phase, the remaining colloidal silica dissolves away, leaving only an amorphous aluminosilicate in the solid phase, which can then rearrange through interaction with the silicates anions in solution. As discussed in a companion study, the aluminosilicate precipitate formed during aging serves as the precursor for nuclei which induce the cyrstallization of NaY zeolite.

Effect of room temperature aging on low temperature transformation of retained austenite

The effect of room temperature aging on the stabilization and low temperature transformation of retained austenite in a low alloy steel (SAE 52100) was studied. It was found that the amount of retained austenite which transformed on subcooling to 250 °K, 200 °K, and 150 °K decreased rather rapidly as the aging time at room temperature prior to cooling was extended up to 16 hours. Little retained austenite transformed by further extending the aging time at room temperature beyond 16 hours.