Growth Of Precipitates Research Articles

Current and projected hydroclimatic changes in the Baltic and Arctic sea basins in the territories of Belarus and Russia

The article presents an assessment of current changes in air temperature, precipitation, snow and river runoff in the Baltic and Arctic Seas basins in the territories of Belarus and Russia. It is shown that the observed positive air temperature trends during the winter season are associated with the sea level pressure distribution in the North Atlantic and NAO indices. In summer, the temperature growth is correlated strongly with the Atlantic multi-decadal oscillation. Changes in the precipitation regime are synchronized with an increase in the sea level pressure in the baroclinic active zones of the Atlantic Ocean, which led to the precipitation increase in Europe since the second half of the 20th century. Interdecadal precipitation fluctuations in the study region are associated with the dynamics of the circumpolar vortex and Arctic oscillation (AO) indices. In winter, a precipitation increase is observed in the negative AO phase and is caused by an increase in the frequency of southern cyclones. In summer, when the AO phase is negative, the cyclonic activity decreases, and the precipitation growth is associated with convective processes in the atmosphere. Snow precipitation and snow water equivalent are decreasing during recent decades due the air temperature significant growth. That led to the spring floods height decreasing in the region. In the next 30 years, a decrease in the winter air temperature in the Baltic Sea basin and its increase in the Arctic Sea are expected. In summer, the air temperature increase will slow down on the descending AMO branch in the coming decades. In the precipitation regime, the growth of seasonal and daily total precipitation is expected.

Experimental and Simulation Study for the Influence of Thermal Pre-Deformation on Subsequent Aging Precipitation Kinetics of Al-Zn-Mg-Cu Alloy.

Deformation and heat treatment are important means to strengthen aluminum alloys. However, the influence mechanism of pre-strain on aging precipitation kinetics and its effect on mechanical properties are still not clear. In this work, uniaxial isothermal tensile tests with different strains and artificial aging treatments for Al-Zn-Mg-Cu alloys have been carried out. Then, a model describing the precipitates kinetic behavior has been developed to investigate the effect of thermal pre-strain on subsequent aging precipitation kinetics and peak aging microhardness based on the microstructure characterization by TEM, SAXS and XRD tests. In addition, the role of dislocations on the aging precipitation kinetics is also explored. The experimental results show that the peak aging microhardness of the Al-Zn-Mg-Cu alloy reveals a tendency to decrease and increase and then the peak aging time firstly decreases and then keeps almost constant with the increase in the strain. The calculations demonstrate that the precipitate average size almost remains unchanged, while the precipitate volume fraction decreases and then increases with the increase in strain, which is consistent with the change in peak aging microhardness. It also indicates that dislocations can promote precipitate nucleation and growth, while the actual effect depends on the dislocation density, which is closely dependent on the pre-deformation condition, especially for the precipitate nucleation. In particular, when the dislocation density after thermal pre-deformation is not enough, it will slightly inhibit precipitate nucleation but promote precipitate growth, which could shorten the peak aging time, with the peak aging strength being guaranteed.

THE INFLUENCE OF WINTER-SPRING TEMPERATURES AND PRECIPITATION ON THE SPRING FLOOD WAVE

The complex influence of meteorological conditions on the first (April) wave of spring-summer flooding of the mountain rivers was studied by the example of 34 mid-size and small rivers of the Altai-Sayan mountain country covering more than 2,000,000 km2 of the Central Asia territory. System-analytical modeling was employed to describe the complex dependence of April river runoff on air temperatures and precipitation for December-April. The impact of factors was quantitatively assessed through solving the inverse mathematical problem and using 1,760 values of river runoff for 1951-2019, meteorological data and carto- graphic information on the relief and landscape structure of river basins calculated in ArcGIS 10.2. Precipitation accumulated in December-March as snow cover had a positive effect on runoff only in case of proximity of winter temperatures to their long-term mean values. At low April temperatures, river runoff increased along with the growth of current precipitation, while at temperature rise it decreased. The established dependencies of the first flood wave on meteorological factors are of great importance for effective preventing adverse effects of spring floods in the mountain regions.

Micro-dynamic process of cadmium removal by microbial induced carbonate precipitation

Microbially induced carbonate precipitation (MICP) is a technique used extensively to address heavy metal pollution but its micro-dynamic process remains rarely explored. In this study, A novel Cd-tolerant ureolytic bacterium DL-1 (Pseudochrobactrum sp.) was used to study the micro-dynamic process. With conditions optimized by response surface methodology, the removal efficiency of Cd2+ could achieve 99.89%. Three components were separated and characterized in the reaction mixture of Cd2+ removal by MICP. The quantitative-dynamic distribution of Cd2+ in different components was revealed. Five synergistic effects for Cd2+ removal were found, including co-precipitation, adsorption by precipitation, crystal precipitation on the cell surface, intracellular accumulation and extracellular chemisorption. Importantly, during Cd2+ removal by MICP, the phenomenon that crystalline nanoparticles adhere to the cell surface, but without any micrometer-sized precipitation encapsulated bacterial cells was observed. This indicated that the previously studied model of bacterial cells as nucleation sites for metal cation precipitation and crystal growth is oversimplified. Our findings provided valuable insights into the mechanism of heavy metals removal by MICP, and a more straightforward method for studying biomineralization-related dynamic process.

Sequential enlarging Lu2O3:Eu phosphor mono-spheres into near micro-meter size range by controlled nucleation and growth for attaining optimum photoluminescence properties

Uniform phosphor mono-spheres have received continuously increasing attention owing to their excellent luminescence properties. Submicron/near micron-sized Lu2O3:Eu mono-spheres were successfully prepared by a facile and modified homogeneous precipitation technique from corresponding single-source precursor of Lu(OH)CO3:Eu⋅nH2O, without the assistance of any dispersants. The sizes of the precursor spheres can be tuned in the range of 56–790 nm via controlling the primary particle nucleation and particle growth in the homogeneous precipitation. After calcination at 1000 °C, the synthesized precursor spheres (165–790 nm) were converted to Lu2O3:Eu (110–630 nm) without changing their original spherical shape and excellent dispersion. The particle size-dependent photoluminescence properties of Lu2O3:Eu mono-spheres were investigated in detail. Enhanced photoluminescence intensity, shorter lifetime, higher external quantum efficiency and almost the same CIE chromaticity coordinates were observed for a particle size of 480 nm. Moreover, temperature-dependent photoluminescence spectra indicated the obtained phosphor mono-spheres have good thermal stability.

Phase-field modeling of the clustering of transmutation element rhenium in irradiated tungsten

Incident neutrons in irradiated W can cause the formation of solid transmutation elements, of which Rhenium (Re) is the most abundant. We apply the phase-field method to investigate the clustering and growth of the Re-rich precipitate in irradiated W based on the spinodal decomposition mechanism, and their effects on the mechanical and thermal properties of W. Needle-like precipitates are reproduced and comparable to experimental observations. We then vary the irradiation dose and temperature to study their influences on the microstructure evolution of the Re-rich precipitate. Simulation results show that the average diameter, the number density, and the coverage rate of the precipitates significantly increase with the increase of the irradiation doses but slightly increase with the increase of the temperature. The effects of the Re-rich precipitate on the mechanical and thermal properties of W are also investigated. Results show that the Vickers hardness increase and the thermal conductivity degrade due to the formation of the Re-rich precipitate, especially at high irradiation doses. Conventional simulation methods can hardly handle the effect of the needle-like precipitates on the mechanical and thermal properties. In this work, we compare these two properties by using needle-like precipitates and circular precipitates. Our results clearly show that the needle-like precipitates give a better consistency with experimental results of the Vickers hardness increase, and reveal the anisotropic ability of the heat transfer in neutron-irradiated W. The current results can provide a systematic understanding of the Re clustering behavior from the microstructure evolution to its influences on the mechanical and thermal properties of W materials.

Modelling dynamic precipitation in pre-aged aluminium alloys under warm forming conditions

This work presents a model for deformation enhanced precipitate growth and coarsening kinetics in pre-aged 7xxx aluminium alloys under warm forming conditions (100 to 200 °C). A multi-class Kampmann–Wagner framework is used to describe the evolution of precipitate size distribution, where the effect of deformation is incorporated through enhanced solute diffusivity resulting from deformation induced excess vacancies. A classical phenomenological model is used to describe the accumulation of excess vacancies. The model is validated with experimental warm deformation data from the literature, and applied to investigate a wide range of deformation conditions to predict the effect of strain, strain rate and temperature on precipitate growth and coarsening kinetics. It is demonstrated that the interaction of solute supersaturation and excess vacancy concentration can lead to complex non-monotonic precipitate growth rate variation for certain regimes of strain rate and temperature.

Understanding Precipitate Growth Kinetics at Ultra-High Hydrostatic Pressures

In this work, we have studied the precipitate growth behavior of a metal matrix when subjected to hydrostatic pressure. We utilized Zenner-Frank phase field kinetics with integrated free energy density functional based on volumetric strain energy. We studied the precipitate growth up to 2 GPa under varying bulk modulus of the precipitate phase. We observed that subjecting to hydrostatic pressure influences the growth kinetics by reducing the precipitate growth under time evolution. In addition, the bulk modulus of the precipitate has shown an abnormality in the growth behavior compared to general observations under hydrostatic pressure. This work contributes to the smart tailoring of novel materials to reduce detrimental impacts on holistic material properties, used in large hydrostatic pressure applications.

Influence of welding parameters on mechanical, microstructure, and corrosion behavior of friction stir welded Al 7017 alloy

Fusion welding of age-hardenable high strength aluminum (Al) alloys can be challenging due to the propensity of these alloys to develop solidification-related issues such as porosity and microcracking. A solid-state welding technique, such as friction stir welding (FSW), offers an excellent alternative to fusion welding by minimizing solidification-related defects in high strength Al alloys. While high quality welds of high strength Al alloys are possible with FSW, the process is highly dependent on the welding parameters. The present study attempts to correlate welding parameters to weld quality using a systematic approach spanning microscopic to macroscopic length scales. Mechanical and corrosion testing shows the influence of the traverse speed on the different weld zones. Higher traverse speed shows higher yield strength (∼287 MPa) and better re-passivation corrosion resistance (∼ −0.958V) as compared to slower traverse speed weld yield strength of ∼264 MPa and re-passivation corrosion resistance of ∼ −0.97V. The dissolution, reprecipitation, growth, and coarsening of precipitates in the weld zones have been validated via detailed differential scanning calorimetry (DSC) and microstructural evaluation using transmission electron microscopy (TEM), revealing the effect of welding parameters. In addition, the mechanical and corrosion properties of the weld improved with post-weld heat treatment, further substantiated with microscopy detailing the changes in precipitate morphology in the weld zones. Finally, some guidelines are provided to assist in selecting parameters for FSW of age hardenable high strength Al alloys to control the width of the HAZ.

Is There Spatial and Temporal Variability in the Response of Plant Canopy and Trunk Growth to Climate Change in a Typical River Basin of Arid Areas

The response of plants to climate change has become a topical issue. However, there is no consensus on the synergistic processes of the canopy and trunk growth within different vegetation types, or on the consistency of the response of the canopy and trunk to climate change. This paper is based on Normalized Difference Vegetation Index (NDVI), tree-ring width index (TRW) and climate data from the Irtysh River basin, a sensitive area for climate change in Central Asia. Spatial statistical methods and correlation analysis were used to analyze the spatial and temporal trends of plants and climate, and to reveal the differences in the canopy and trunk response mechanisms to climate within different vegetation types. The results show a warming and humidifying trend between 1982 and 2015 in the study area, and NDVI and TRW increases in different vegetation type zones. On an interannual scale, temperature is the main driver of the canopy growth in alpine areas and precipitation is the main limiting factor for the canopy growth in lower altitude valley and desert areas. The degree of response of the trunk to climatic factors decreases with increasing altitude, and TRW is significantly correlated with mean annual temperature, precipitation and SPEI in desert areas. On a monthly scale, the earlier and longer growing season due to the accumulation of temperature and precipitation in the early spring and late autumn periods contributes to two highly significant trends of increase in the canopy from March to May and August to October. Climatic conditions during the growing season are the main limiting factor for the growth of the trunk, but there is considerable variation in the driving of the trunk in different vegetation type zones. The canopy growth is mainly influenced by climatic factors in the current month, while there is a 1–2-month lag effect in the response of the trunk to climatic factors. In addition, the synergy between the canopy and the trunk is gradually weakened with increasing altitude (correlation coefficient is 0.371 in alpine areas, 0.413 in valley areas and 0.583 in desert areas). These findings help to enrich the understanding of the response mechanisms to climate change in different vegetation type zones and provide a scientific basis for the development of climate change response measures in Central Asia.

Seasonality and Ecological Suitability Modelling for Anthrax (Bacillus anthracis) in Western Africa.

Simple SummaryAnthrax is a globally distributed, neglected, underreported, soil-borne zoonotic disease. In West Africa, the disease is hyper-endemic, severely affecting the livestock sector. Many challenges exist to control the disease in this region, particularly constraints on financial and human resources. Therefore, methods that can be utilized to improve reporting, guide and prioritize surveillance and control activities and rationalize the allocation of limited resources are crucial. In this study, we showed how to optimize the use of fragmented, heterogeneous and limited precise reporting data of anthrax in Burkina Faso, Ghana, Togo, Benin and Niger to understand risk periods as well as identify and predict risk areas. To achieve this, we used anthrax data from different databases in combination with environmental and climate variables and geospatial remote sensing techniques. Our study demonstrated that the number of anthrax outbreaks by month increase with the increasing monthly rates of change in precipitation and normalized difference vegetation index (NDVI) during the transition period from the dry to the wet season. Livestock density, precipitation, NDVI and alkaline soils were the main predictors of anthrax suitability in the region. Our findings on anthrax seasonality and ecological suitability can inform surveillance, prevention and control programs undertaken by animal and public health authorities and enhance collaborative One Health strategies.Anthrax is hyper-endemic in West Africa affecting wildlife, livestock and humans. Prediction is difficult due to the lack of accurate outbreak data. However, predicting the risk of infection is important for public health, wildlife conservation and livestock economies. In this study, the seasonality of anthrax outbreaks in West Africa was investigated using climate time series and ecological niche modeling to identify environmental factors related to anthrax occurrence, develop geospatial risk maps and identify seasonal patterns. Outbreak data in livestock, wildlife and humans between 2010 and 2018 were compiled from different sources and analyzed against monthly rates of change in precipitation, normalized difference vegetation index (NDVI) and land surface temperature. Maximum Entropy was used to predict and map the environmental suitability of anthrax occurrence. The findings showed that: (i) Anthrax outbreaks significantly (99%) increased with incremental changes in monthly precipitation and vegetation growth and decremental changes in monthly temperature during January–June. This explains the occurrence of the anthrax peak during the early wet season in West Africa. (ii) Livestock density, precipitation seasonality, NDVI and alkaline soils were the main predictors of anthrax suitability. (iii) Our approach optimized the use of limited and heterogeneous datasets and ecological niche modeling, demonstrating the value of integrated disease notification data and outbreak reports to generate risk maps. Our findings can inform public, animal and environmental health and enhance national and regional One Health disease control strategies.

Modelling the Effect of Deformation on Discontinuous Precipitation in Magnesium—Aluminium Alloy

Magnesium–Aluminium alloys can decompose from a supersaturated solid solution by either continuous or discontinuous precipitation. Deformation prior to precipitation has been shown to strongly suppress the discontinuous precipitation mode and promote continuous precipitation. In this work, a model is used to explore the interaction between deformation and precipitation in the Mg–Al system. It has been shown that accelerated nucleation of continuous precipitates on dislocations is predicted to have the dominant effect in suppressing discontinuous precipitation by reducing the solute supersaturation. A secondary effect is the direct role played by twins in the deformed structure, which act as impenetrable barriers to discontinuous precipitate growth. However, even in the deformed case, small regions of discontinuous precipitation are still observed. It is proposed that this is due to the high level of strain concentration expected in the grain boundary regions, which provides a locally enhanced driving force for the migration of grain boundaries such that limited discontinuous precipitation occurs before continuous precipitation becomes established.

Reducing the spin‐up of a regional NWP system without data assimilation

AbstractIn both operational and research settings, kilometre‐scale regional numerical weather prediction (NWP) models are often initialised by interpolating analyses from a global modelling system on to the finer regional grid. When initialised in this way (known as a cold start), the first few hours of the forecast are characterised by a rapid growth of precipitation as the system develops convective‐scale structures. This is the well‐known spin‐up problem. Spin‐up effects limit the utility of cold‐start models for short‐range forecasting of severe weather events and model development activities. In this article, we present a method for reducing the spin‐up of regional NWP models, without data assimilation (DA). The basis of our method is periodically to insert large‐scale information from global model analyses into a continuously cycling regional model, thus updating the large scales whilst preserving fine‐scale structures. We refer to this as a warm start. Our method is tested in a regional model over Darwin, for a 10‐week period in the 2016/2017 wet season. It is shown that warm‐starting indeed reduces the spin‐up of precipitation significantly in the first 6–12 hr of the forecast compared with cold‐starting. Full objective verification against both radar and satellite observations reveals that precipitation forecast skill is also improved during this time. In addition, the large scales remain closer to global analyses (taken as a best guess of reality) than in a free‐running model in which the large scales are updated only via the lateral boundary conditions. Our warm‐start technique thus provides a considerable improvement on standard cold‐starting and could also be integrated into a regional modelling system with full convective‐scale DA as a means of reducing analysis errors on large scales.

Importance of timing: Vulnerability of semi-arid rangeland systems to increased variability in temporal distribution of rainfall events as predicted by future climate change

Natural resources of semi-arid rangelands in the (sub-)tropics are major pillars of food security and livelihoods to millions of people. Besides increasing pressure due to human population growth, high spatial and temporal variability in precipitation leading to highly erratic production of primary biomass has high potential to render the exploitation of ephemeral concentrations of these resources unsustainable. While future climate models predict a general decrease in precipitation for many semi-arid rangelands, the increase in variability of rainfall and its dynamics are important aspects in assessments of climate change impact that only recently gained scientific attention. Building on a spatially-explicit, agent-based model of free-ranging livestock herds in semi-arid rangelands (RaMDry) that accounts for the metabolic energy budget of foraging animals, we assessed the vulnerability of rangelands and livestock production systems as a result of the effects of ongoing changes in precipitation and its variation, as well as its temporal distribution. Based on a coupled-reservoir model conceptually relying on a two-stage cascaded linear reservoir, we developed, implemented and validated a refined forage production module in RaMDry to predict primary productivity of semi-arid grassland and its impacts on livestock production from daily rainfall. Our results show a highly significant effect of increased temporal diffusion of precipitation events on the ecosystem and its productivity. The anticipated diminution in total precipitation and increased inter-annual variation indicated no severe aggravation of the general situation for livestock keepers in terms of system productivity. However, alterations in timing of individual precipitation events resulted in substantial temporal reduction of forage resources in terms of their quantity and quality and major negative impact on livestock body weights. Our findings shed light on the profound consequences of inter-seasonal dry spells as one important aspect of climatic changes on livestock production systems in (sub-)tropical, semi-arid rangelands.

Studies on softening behavior and mechanism of heat-affected zone of spray formed 7055 aluminum alloy under TIG welding

In this investigation, fine micro-zone specimens in the heat-affected zone (HAZ) of TIG welded spray formed 7055 aluminum alloy were obtained by heat treatment method. The softening behavior and mechanism of HAZ of this alloy under single pass TIG welding were investigated. Severe non-uniformities of microstructures and mechanical properties were found, according to which the HAZ was divided into the solid solution zone and the over-aging zone. The most heavily softened area of HAZ occurred in the over-aging zone at the position corresponding to the peak thermal cycling temperature of 230–350 °C. The lowest microstructures value was 105 HV, the lowest tensile strength was about 410 MPa. The elongation was slightly higher than that of the base material. The main causes of softening in the over-aging zone were the dissolution of the coherent precipitate η′ and the growth and coarsening of the non-coherent precipitate η.Thermal cycle temperature in the solid solution zone was about 350–536 °C. Mechanical properties in this zone were higher than those of the over-aging zone. After natural aging, mechanical properties recovered to more than 90% of the base material. Microhardness reached 180 HV and tensile strength reached 570 MPa when the thermal cycle temperature was 450 °C. At the same time, the elongation in the solid solution zone was higher than that of the base material. The high mechanical properties were the results of the combined action of the increased ratio of large angle grain boundaries, the increased solid solubility and the formation of coherent GPI zone.

Origin of morphological variation of grain boundary precipitates in titanium alloys

Morphological variations of grain boundary (GB) allotriomorphs and widmanstatten sideplates (WS) of α precipitate in a β titanium alloy, have been systematically investigated by combining three-dimensional (3D) phase-field simulations, 3D experimental characterization and crystallographic orientation analysis. The inclination angle, θ, between the habit plane of the GBα and the hosting GB plane is found to dictate the morphologies of GB precipitates. For the first time, three distinct regimes of α morphology at a β GB, separated by two critical angles (θc1, θc2) are observed: θ≤θc1, GBα alone decorates the GB as a continuous layer; θc1<θ≤θc2, α precipitate appears as a mixture of GBα and a WS emanating from it; θ>θc2, WS alone grows directly from bare β GBs. The dramatic morphological variation owes its origin to the dynamic interplay between the spreading along GBP and the intragranular growth of the GB precipitate, and its dependence on θ.

Effect of Natural Aging on Precipitation Strengthening Behaviors in Al-Mg-Si Alloy

Natural aging (NA) is unavoidable in Al-Mg-Si alloys during actual manufacturing. Revealing the reasons for the alloy strength reduction caused by the negative NA effect is of great significance to research and practice. In this work, atom probe tomography (APT) and transmission electron microscopy (TEM) were employed simultaneously to study the effect of NA on precipitates and their contributions to the strength of Al-Mg-Si alloys. It was found that the numerous clusters formed after significant NA are unstable and will dissolve into the matrix during initial AA. However, a few stable clusters are undissolved and will result in abnormal growth of β″, which then transforms to β′. Due to the decrease of nucleation sites resulting from the abnormal growth of precipitates, more solute atoms remain in the matrix. The calculation results show that the strengthening of the solid solution atoms is much smaller than that of large-sized β′, which is much less than that of fine β″. Therefore, lengthy NA causes a significant reduction in AA strength of the Al-Mg-Si alloy.

Phase field simulations of FCC to BCC phase transformation in (Al)CrFeNi medium entropy alloys

Microstructure simulations for quaternary alloys are still a challenge, although it is of high importance for alloy development. This work presents a Phase field (PF) approach capable of resolving phase transformation in a multicomponent system with a simple and effective way to include the thermodynamic and kinetic information for such a complex system. The microstructure evolution during diffusional transformation between FCC and BCC phase at 700 °C for AlCrFeNi alloys was simulated, accounting for composition dependence and off-diagonal terms in the diffusion tensor. The reliability of the presented PF method is validated by comparing the 1-D simulation results with simulations by Diffusion Module (DICTRA) of Thermo-Calc Software. Additionally, 2-D PF simulations of precipitate growth and Ostwald ripening are performed for different alloy systems, and the coarsening behavior is compared. Results showed that thermodynamic and kinetic information is accurately described in the applied PF method. The simulation results show that the diffusion behavior is influenced evidently by variations in the amounts of the different elements in the system. These findings demonstrate the necessity of applying accurate thermodynamic and kinetic models to fully understand the complex interdiffusion behavior in high and medium entropy alloys.

Liquid cell transmission electron microscopy reveals C-S-H growth mechanism during Portland cement hydration

We report the first application of in-situ liquid cell transmission electron microscopy (LC-TEM) to research hydration reactions of nano OPC, providing nanoscale insight into early reaction mechanisms. We demonstrate that the formation and growth of C-S-H precipitates starts through lateral growth of planar silicate sheets, but soon continues in all directions resulting in a 3D microstructure. Furthermore, nanocrystalline C-S-H structures with sizes between 5 nm to 10 nm were observed inside the amorphous or highly disordered C-S-H matrix, denoting that C-S-H growth is conformed to layered structure model. Crack formation and propagation inside C-S-H precipitates confirms the presence of increasing lattice strain due to growing defects that limits the growth of a fully crystalline structure by buckling and separating the sheets. The rolling up and crumbling of C-S-H sheets promotes the formation of new embryos, leading to the growth of precipitates in all direction and finally their coalescence.

The effects of Nb additions on the microstructure evolution in Cu–9Ni–6Sn alloy

Cu–9Ni–6Sn specimens with different Nb contents ranging from 0 to 0.22 wt% were prepared by a vacuum induction furnace, and needle-like NbNi3 particles were found at the grain boundaries and interior after solution treatment. The results indicated that these NbNi3 particles suppressed the discontinuous precipitation (DP) growth during aging treatment. By using Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation and Arrhenius equation, the kinetics of DP is also figured out and the activation energy (Q) of the DP in Cu–9Ni–6Sn-xNb (x = 0, 0.05, 0.22 wt%) alloys are 75.8 kJ/mol, 80.9 kJ/mol and 88.5 kJ/mol, respectively, indicating that the atom diffusion for producing DP is more difficult in Nb-bearing alloys, and the formation of DP is inhibited correspondingly. What's more, the lamellar spacing (S) of DP increased and the growth rate of DP decreased in the with the Nb-bearing Cu–9Ni–6Sn alloy.