Transformation Behavior Research Articles

Unveiling the enhancing mechanism of cyclic stability in Tb doped Ni-Mn-Sn Heusler alloys

Rare-earth (RE) doping has been demonstrated as a feasible approach to improve the cyclic performance of Ni-Mn-based Heusler alloys, but the current demonstration of underlying mechanism is simply ascribed to strengthening of the grain boundary cohesion. In this work, the effects brought by RE doping on microstructure, stress induced martensitic transformation behavior and cyclic stability of Ni-Mn-based alloys were systematically investigated. By Tb doping, a stable adiabatic temperature change (|ΔTad|) of ∼ 5.5 K over 1000 cycles with no significant degradation was obtained in (Ni43Mn47Sn10)99.5Tb0.5. (1) Through the in-situ digital image correlation strain measurement and in-situ SEM observation upon loading process, it revealed a multipoint nucleation of the martensitic transformation across the specimen arising from the intergranular NiSnTb secondary phase as nucleate sites, which weakens the strain concentration and suppresses the crack tendency. (2) The multipoint nucleation promotes the transformation volume fraction, making the large |ΔTad| could be driven by a small transformation strain (Δεtr) and (Ni43Mn47Sn10)99.5Tb0.5 yields a |ΔTad/Δεtr| up to 8.7 K %−1. Such reduction in applied strain further alleviates the extension of the cracks. Both the two factors brought by Tb doping in (Ni43Mn47Sn10)99.5Tb0.5 give rise to the enhancement in cyclic stability of the large elastocaloric effect.

A study on the occurrence modes and distribution characteristics of sulfur and mercury in coal gasification slag

Although coal gasification is recognized as a core technology for clean coal utilization, S and Hg can migrate to gas, wastewater, and slag during the gasification process, causing environmental pollution. It is well known that S and Hg have a strong affinity. Therefore, the interaction between S and Hg during the gasification process warrants further investigation. In this study, the occurrence modes and distribution characteristics of S and Hg in gasification slag were systematically investigated using multiple treatments and various characterization techniques. The results showed that sulfur in the gasification slag exists predominantly as organic sulfur, while mercury mainly exists as HgS/silicate-bound Hg. Although the relative enrichment index of Hg (RE < 0.7) indicates its high volatility, a more pronounced enrichment effect for mercury of fine slag was indicated by its much higher RE than coarse slag. When exploring the relationship among the contents of C, S, and Hg and specific surface area in gasification slag, it was found that the correlation between S and Hg content in fine slag was the strongest, with a correlation coefficient (R2) of 0.96, indicating a significant influence of sulfur content in fine slag on mercury content. Additionally, it was observed that the S and Hg contents in gasification slag increased with the decrease of particle size and density. These results provide an important understanding of the distribution, migration, and transformation behavior of S and Hg during coal gasification, as well as a certain theoretical support and technical basis for the resource utilization of gasification slag.

Photochemical transformation of liquid crystal monomers in simulated environmental media: Kinetics, mechanism, toxicity variation and QSAR modeling

Liquid crystal monomers (LCMs) are a new class of emerging pollutants with high octanol-water partition coefficients; however, their transformation behavior and associated risk to environments with high organic matter content has rarely been reported. In this study, we investigated the photodegradation kinetics, mechanism, and toxicity variation of 23 LCMs on leaf wax models (e.g., organic solvents methanol and n-hexane). The order of the photolysis rates of these LCMs were biphenylethyne LCMs > phenylbenzoate LCMs > diphenyl/terphenyl LCMs under simulated sunlight, while the phenylcyclohexane LCMs were resistant to photodegradation. The phenylbenzoate and biphenylethyne LCMs mainly undergo direct photolysis, while the diphenyl/terphenyl LCMs mainly undergo self-sensitized photolysis. The main photolysis pathways are the cleavage of ester bonds for phenylbenzoate LCMs, the addition, oxidation and cleavage of alkynyl groups for biphenylethyne LCMs, and the cleavage/oxidation of chains attached to phenyls and the benzene ring opening for diphenyl/terphenyls LCMs. Most photolysis products remained toxic to aquatic organisms to some degree. Additionally, two quantitative structure-activity relationship models for predicting kobs of LCMs in methanol and n-hexane were developed, and employed to predict kobs of 93 LCMs to fill the kobs data gap in systems mimicking leaf surfaces. These results can be helpful for evaluating the fate and risk of LCMs in environments with high content of organic phase.

Effect of prior austenite grain size on austenite reversion, bainite transformation and mechanical properties of Fe-2Mn-0.2C steel

To elucidate the response of austenite reversion and subsequent bainite transformation behavior to the prior austenite grain (PAG) size, the transformation kinetics and amount of reverted austenite in the intercritical region, the subsequent bainite transformation kinetics, and the tensile properties were investigated by dilatometers, scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy, and the mechanical tests. The results show that, when annealed at 730 °C, fine-grained specimens exhibit faster reverted austenite transformation rate than coarse-grained specimens due to the presence of more PAG boundaries. As the intercritical temperature rises to 760 °C, more intragranular globular austenite forms in the coarse-grained specimen, which accelerates the reverted austenite transformation rate. Compared to fine-grained specimens, coarse-grained specimens exhibit faster bainite transformation and higher amount of bainitic ferrite. The microstructure after austempering consists of intercritical ferrite, bainitic ferrite, RA and fresh martensite. With increasing the austempering time, more bainitic ferrite is formed and the amount of RA and fresh martensite decreases. With increasing the austempering time, the increase in the amount of bainitic ferrite leads to an increase in the yield strength, while the decrease in the amount of RA leads to a decrease in the elongation. Moreover, compared with coarse-grained specimens, the finer microstructure in fine-grained specimens improves yield and tensile strengths, while higher amount of RA contributes to larger uniform and total elongations.

Comparing Leader and Follower Perceptions of Transformational Leadership: Implications for Organizational Commitment and Performance.

Purpose: The transformational leadership paradigm has been a focal point in organizational research, but a critical methodological question remains: whose perception of transformational leadership should be relied upon for accurate evaluation? This study addresses this question by examining the differences that arise depending on whether the leader’s or their followers' assessment of the leader's transformational leadership is used. Methodology: Transformational leadership behavior (TLB) perception data were collected from both leaders (n=372) and their followers (n=892) to analyze its impact on organizational commitment (OC) and organizational performance (OP). Structural equation modeling was employed to reveal the impact of TLB on OP from both leader and follower perspectives. Findings: Both leader and follower perception models exhibit a significant positive effect of TLB on OP. However, the mechanisms differ substantially. In the follower perception model, the impact of TLB on OP is almost entirely mediated through OC. Conversely, in the leader perception model, the impact of TLB on OP is split between the direct effect of TLB on OP and the mediated effect through OC on OP. Unique Contribution to Theory, Practice, and Policy: These findings have significant implications for interpreting past research on transformational leadership and future methodologies. The study contributes to the literature by offering a comprehensive understanding of the relationships between TLB, OC, and OP, particularly in the public sector, utilizing a large-scale sample.

Exploring the effects of austenitizing conditions on the heterogeneous microstructure and mechanical properties of 11Cr–11Ni–Ti–Mo maraging stainless steel: Breakthrough in the strength-ductility trade-off

Based on the microstructure analysis, the present research investigated the influence of various austenitizing conditions on the transformation behavior of intermetallic compound particles, i.e. η-Ni3Ti, and the reversed austenite during ageing treatment in Ti–Mo maraging stainless steel, as well as the related mechanical properties. The results revealed numerous tiny rod-like intermetallic compound particles, i.e. η-Ni3Ti, having a Burgers orientation relationship, i.e., {101}α′//{0001}η ; <111‾>α′//<112‾0>η, with the martensite matrix, as well as blocky, lath, and granular reversed austenite of various sizes distributed within the tempered martensite matrix. Regardless of the austenitizing treatment condition, more reversed austenite was found in the samples aged at 520 °C than in those aged at 640 °C. Although this finding was not consistent with the Thermo-Calc predictions, it should be associated with the thermal stability of reversed austenite at different ageing temperatures. In other words, the greater amount of reversed austenite that formed at 640 °C did not remain at room temperature due to secondary martensite transformation during cooling, as was verified by EBSD analysis.

Impact of Transformational Leadership Style of School Heads on Altruism Organizational Citizenship Behavior of Teachers.

The purpose of this study was to identify the effects of principals' transformational headship style on teachers' Altruism organizational citizenship behavior (AOCB). This specific research fills the existing gap in the relationship between these variables. The study included entire Heads and Teachers of Public Sector Secondary Schools in 4 Southern districts of Khyber Pakhtunkhwa as the population. By using L.R Gay's (2003) sample size ratio formula, 8% of the population was selected as samples for the study. For data collection,the first instrument was the Short Form Multifactor Leadership Questionnaire (MLQ) 1995 developed by Bass and Avolio to test the transformational leadership behavior of Heads and the second instrument was the organizational-citizenship-behavior scale (OCBS), produced by Podsakoff &amp; colleagues (1990) to assess the rank of the Altruism citizenship behavior of teachers in Southern districts of Khyber Pakhtunkhwa (KP). The data were organized and the responses to each item were analyzed using relevant statistics. The findings of the study exposed that there is a significant relationship between the Transformational Leadership behavior of Heads and the Altruism Organizational-Citizenship Behavior(AOCB) of Teachers of Secondary Schools in the southern districts of Khyber Pakhtunkhwa (KP) province

Mitigating Workplace Burnout Through Transformational Leadership and Employee Participation in Recovery Experiences.

Description Burnout is a complex organizational phenomenon that diminishes employee well-being and overall organizational productivity. Researchers propose that leadership style contributes to employees' well-being, which impacts employee productivity. Organizations and leaders must address the causes of burnout and promote techniques employees can use to mitigate burnout, such as employee participation in recovery experiences. Recovery experiences are non-work activities that create positive outlooks and restore the energy needed to focus on one's work. This literature review examines current research in employee recovery experiences, conservation of resource theory (COR), burnout, and transformational leadership theory. Studying burnout through the lens of COR shows how important resource gain and recovery activities are to healthy employees and their job performance within the organization. The research reviewed suggests that transformational and transactional leadership styles have higher probabilities of promoting employee participation in recovery experiences than passive avoidant leadership style. The literature consistently showed burnout as a significant organizational phenomenon negatively affecting productivity, employee well-being, and turnover rates. The literature revealed that mitigating burnout happens through participation in recovery experiences. The literature on leadership styles supports the assumption that leaders play a significant role in employee well-being, group identity, and organizational climate. Leaders who desire to mitigate employee burnout will benefit from research that links transformational leadership style behaviors and employee participation in recovery activities.

Interpersonal and Organizational Dimensions of Leaders’ Transformational Behaviours Measured by LPI©

Interpersonal and Organizational Dimensions of Leaders’ Transformational Behaviours Measured by LPI©

Multilevel study of transformational leadership and work behavior: job autonomy matters in public service

PurposeThis study aims to use self-determination and social exchange theory to investigate how transformational leadership influences employees’ motivation for their work behaviors, with job autonomy serving as a mediator. This study hypothesized that transformational leadership could promote employees’ autonomy in performing their tasks, leading to the development of innovative work behaviors and organizational citizenship behaviors.Design/methodology/approachUsing a multilevel approach, data was collected from 409 public service employees across 39 departments.FindingsThe findings indicate the significant impact of transformational leadership on shaping employees’ innovative work and organizational citizenship behavior. Notably, job autonomy emerges as a pivotal mediator, facilitating the positive effects of transformational leadership by empowering employees to explore innovative tasks beyond their prescribed roles, thereby enhancing team effectiveness and employee engagement.Originality/valueThis study’s originality lies in its innovative use of multilevel analysis to reveal job autonomy’s mediating role, offering fresh insights into promoting innovation and organizational in public service settings.

Comparative study on microstructure, mechanical and high temperature oxidation resistant behaviors of SLM IN718 superalloy before and after heat treatment

The microstructure, phase transformation behavior, heat treatment effects, and their impacts on the mechanical properties and high-temperature oxidation resistance of IN718 nickel-based superalloy processed by selective laser melting (SLM) both before and after heat treatment was systematically investigated. The heat treatment process involved a two-step aging at 720 °C for 8 h plus 620 °C for 10 h with a controlled slow cooling rate of 10 °C/min. Through the comprehensive use of scanning electron microscopy (SEM), X-ray diffraction (XRD), electron backscattering diffraction (EBSD), and transmission electron microscopy (TEM), the evolution of the microstructure and its mechanism of influence on material properties were revealed. The study identified the formation of γ phase, γ′ phase, γ'' phase, δ phase, and Laves phase during the SLM forming process. Heat treatment played a key role in improving the microstructure and properties of the SLM-processed alloy, with experimental results showing that the mechanical performance and high-temperature oxidation resistance were significantly enhanced after heat treatment. Specifically, the material after heat treatment exhibited a yield strength of 1472 MPa, a tensile strength of 1608 MPa, and an elongation of 9.2%, which represented increases of 76.5%, 38.4%, and 16.5% respectively, compared to the as-printed alloy. Moreover, the oxidation resistance at 1000 °C of the heat-treated samples improved significantly, with weight loss reduced from −0.17 mg/cm2 before heat treatment to −0.15 mg/cm2. Microstructural analysis further indicated that heat treatment optimized the crystal orientation, promoted the formation of more precipitated phases and reduced defects, thereby enhancing the overall performance of the material. This work provides significant scientific insights into understanding and optimizing the IN718 nickel-based superalloy processed by SLM, demonstrating the crucial role of heat treatment in improving its microstructure and properties.

Research on the Migration and Adsorption Mechanism Applied to Microplastics in Porous Media: A Review.

In recent years, microplastics (MPs) have emerged as a significant environmental pollutant, garnering substantial attention for their migration and transformation behaviors in natural environments. MPs frequently infiltrate natural porous media such as soil, sediment, and rock through various pathways, posing potential threats to ecological systems and human health. Consequently, the migration and adsorption mechanisms applied to MPs in porous media have been extensively studied. This paper aims to elucidate the migration mechanisms of MPs in porous media and their influencing factors through a systematic review. The review encompasses the characteristics of MPs, the physical properties of porous media, and hydrodynamic factors. Additionally, the paper further clarifies the adsorption mechanisms of MPs in porous media to provide theoretical support for understanding their environmental behavior and fate. Furthermore, the current mainstream detection techniques for MPs are reviewed, with an analysis of the advantages, disadvantages, and applications of each technique. Finally, the paper identifies the limitations and shortcomings of current research and envisions future research directions.

Factors influencing work engagement of nurses in general hospitals: A cross-sectional study.

This study aimed to examine the level of work engagement and to identify the factors influencing the work engagement of nurses. Work engagement plays a crucial role in enhancing the efficiency of outcomes and the standard of care in nursing and healthcare services. A descriptive predictive design and stratified random sampling was used to select206 nurses from three general hospitals in Naypyitaw, Myanmar.. Research instruments consisted of the demographic data form, the Utrecht Work Engagement Scale, the Global Transformational Leadership Scale, the Survey of Perceived Organizational Support, and the Psychological Capital Questionnaire. The results were explored by applying descriptive statistics and stepwise multiple regression. Overall work engagement was at an average level. Transformational leadership and psychological capital could affect work engagement, explaining 19.34% of the total variance; however, perceived organizational support, age, and work experience did not show any impact on it. The findings recommend that nurse administrators should focus on transformational leadership and psychological capital in formulating strategies to increase nurses' work engagement. The outcomes might providebaseline information for nurse administrators and policymakers by formulating management strategies to enhance nursing leaders' awareness, knowledge, and skills about transformational leadership behaviors and to keep nurses holding self-efficacy, hope, optimism, and resilience of psychological capital in healthcare organizations, which ultimately increase nurses' engagement at work.

Effect of biochar-derived DOM on contrasting redistribution of chromate during Schwertmannite dissolution and recrystallization

Biochar-derived dissolved organic matter (BDOM), is extensively involved in the recrystallization of minerals and the speciation alteration of associated toxic metals. This study investigates how BDOM extracted from tobacco petiole (TP) or tobacco stalk (TS) biochar influences the speciation repartitioning of Cr(VI) in environments impacted by acid mine drainage (AMD), focusing on interactions with secondary minerals during Schwertmannite (Sch) dissolution and recrystallization. TP-BDOM, rich in lignin-like substances, slowed down the Cr-Sch dissolution and Cr release under acidic conditions compared to TS-BDOM. TP-BDOM's higher O/C component exerts a delayed impact on Cr-Sch stability and Cr(VI) reduction. In-situ ATR-FTIR and 2D-COS analysis showed that carboxylic and aromatic N-OH groups in BDOM could interact with Cr-Sch surfaces, affecting sulfate and Cr(VI) release. It was also observed that slight recrystallization occurred from Cr-Sch to goethite, along with increased Cr incorporation into secondary minerals within TS-BDOM. This enhances our understanding of BDOM's role in Cr(VI) speciation changes in AMD-contaminated sites.

Transformation Behaviors and Microstructure Modifications in Hydrogen-Charged Ti–Ni Shape Memory Alloy

AbstractThe effect of hydrogen charging duration on the transformation behavior, microstructural evolution, and dynamic microstructural changes associated with thermoelastic martensitic transformation in Ti–Ni shape memory alloy was investigated. Compared with the uncharged specimen, the martensitic transformation start (Ms) and reverse transformation finish (Af) temperatures increased with charging time, whereas the martensitic transformation finish and reverse transformation start temperatures remained almost unchanged. In situ SEM results were consistent with these behaviors. Upon cooling, the transformation progressed from the center to the surface in charged specimens, indicating a higher transformation temperature in the center than the surface. The latent heat of transformation decreased with increasing charging time, quantitatively attributed to an untransformed region consisting of hydrogen-induced martensite and a hydrogen-affected layer. The hydrostatic effect from those layers on the interior B2 phase was proposed as the origin of the increased Ms and Af temperatures.

Complementary In Situ Characterization of Superelasticity in Fe–Mn–Al–Ni–Ti Shape Memory Alloys by Acoustic Emission, Digital Image Correlation and Infrared Thermography

AbstractCoupled in situ investigations were conducted on a Fe–Mn–Al–Ni–Ti single crystal deformed in compression and two Fe–Mn–Al–Ni–Ti oligo-crystals deformed in tension. Acoustic emission measurements were employed to monitor the degradation of superelasticity and the stabilization of martensite due to dislocation processes. These observations were corroborated by the application of digital image correlation and infrared thermography measurements. A poor strain reversibility and a premature plastification of the parent phase were observed in case of the single crystal due to an unfavourable crystal orientation. A contradictory transformation behaviour of the two oligo-crystals was observed, with one specimen showing a promising strain reversibility and characterisitic signs of degradation, and the other specimen exhibiting a limited strain reversibility due to an unusual confinement of the martensitic phase transformation to an unfavourably oriented grain. In the former case, an increase in the dislocation density within five cycles was detected through a shift of the acoustic signals’ median frequencies. In the latter case, a strong coupling between martensite nucleation and dislocation generation led to a pronounced martensite stabilization after one loading cycle. For all specimens, temporal sequence effects related to the coupling of martensite nucleation and dislocation generation were detected by means of acoustic emission.

Soil Microbial Stress Responses under External Chemical and Physical Environmental Stresses

AbstractSoil microorganisms play a crucial role in maintaining soil ecosystem health. Their metabolic processes are directly impacted by various environmental stresses caused by the increasing release of chemical pollutants and changes in the physical environment due to rapid societal development. This paper aimed to investigate the mechanisms underlying the changes in soil microbial stress responses under various external environmental stresses. The impact of pollutants on soil ecological structure was analyzed by summarizing the stress response patterns of soil microorganisms to inorganic pollutants, organic pollutants, and extreme physical environmental factors. Additionally, the migration and transformation behaviors of various complex pollutants, facilitated by the involvement of soil microorganisms, were investigated. Moreover, a novel approach was proposed for pollutant control, suggesting that manipulating the external physical field of a certain intensity could guide microbial communities and their functions towards controllable evolution within the soil environment. Therefore, this paper was essential for exploring the diversity of soil microbial stress responses, strategically regulating contaminant transport, mitigating risks associated with soil complexity, and ultimately reshaping soil ecological functions.

Assessing the Role of HRM and HRD in Enhancing Sustainable Job Performance and Innovative Work Behaviors through Digital Transformation in ICT Companies

In the era of Industry 4.0, digital transformation has become a cornerstone for modern organizations, fundamentally altering how businesses operate and compete. This study delves into the impact of digital transformation on human resource management (HRM), human resource development (HRD), and employees’ innovative work behaviors and job performance in a rapidly evolving business environment. In conducting a survey among 391 employees from information and communication technology (ICT) companies in China, structural equation modeling was employed to analyze the data. The findings reveal a correlation between digital transformation and innovative work behaviors and job performance, with HRM and HRD playing partial mediating roles. Digital transformation not only optimizes work processes and enhances productivity but also fosters the innovation of business models and processes. Moreover, the research indicates the critical importance of implementing efficient digital systems and processes in promoting an organizational culture of innovation and enhancing employees’ innovative capabilities. Thus, digital transformation is seen as a pivotal strategic tool, altering not just the modus operandi of organizations but also influencing employee behavior and performance.

Transformation behavior of hazardous jarosite into recyclable hematite in a solution with high concentrations of K+ and Na+

Iron in the leaching solution with high K+ and Na+ concentrations was usually precipitated as the typical hazardous and toxic jarosite residues. However, this method of treatment has been greatly restricted by increasingly strict environmental regulations. Here we propose that iron can be precipitated from the solution with high K+ and Na+ concentrations as recyclable hematite products by adjusting the concentration ratio of sodium and potassium ions in the solution. The transformation behavior of jarosite into hematite in high concentration potassium ion and sodium ion solution was explained based on collision theory. The results indicated that in instances where the concentration ratio of Na+/K+ is ≥ 4:1, the iron present in the solution can be effectively precipitated as a recyclable hematite product, as opposed to forming the conventional hazardous jarosite residue, even under conditions where the potassium ion concentration reaches levels as high as 4 g/L. On the other hand, thermodynamic and molecular dynamics simulations indicate that at a temperature of 185 °C, the decomposition transformation of Na-jarosite (32.64 kJ and 7.25 eV) is more energetically advantageous compared to that of K-jarosite (61.07 kJ and 15.31 eV). The results were verified by the leaching solution from smelting industry. The iron content in the residues is above 58%, the sulfur content is below 4%, the zinc content is below 1%, and the total iron concentration in the supernatant is about 4 g/L, reaching the production index of the smelting industry. The green, environmentally friendly, and recyclable separation of iron in a solution with high concentrations of potassium and sodium ions is achieved, which is of great significance for the treatment of iron-containing solution and wastewater in the chemical industry and metallurgy fields.

Larger Recovery Strains in Cast Fe–Mn–Si‐Based Shape Memory Alloys by Reducing Thermal Activation and Optimizing Mn Content

Previous work shows that a maximal recovery strain of 8.4% after being bent at room temperature is realized in annealed cast polycrystalline Fe–Mn–Si‐based alloys because of the reduced annealing twin boundaries. Theoretically, higher recovery strains can be expected at cryogenic deformation by reducing thermal activation. To confirm this idea, martensitic transformation behaviors and the recovery strains after being bent at 77 K are investigated in the cast Fe–(20–26)Mn–5.5Si–8.5Cr–5Ni alloys. Herein, larger recovery strains as high as ≈10.0% are realized in an annealed cast Fe–23Mn–5.5Si–8.5Cr–5Ni alloy after being bent at 77 K. The reduced thermal activation together with suppressed formation of thermal‐induced martensite by optimizing Mn content can account for the larger recovery strain. In these results, a new avenue is opened up for further enhancement of the recovery strain in Fe–Mn–Si‐based shape memory alloys.