Nanoindentation response of anisotropic piezoelectric materials

A three-dimensional finite element model is developed to accurately capture the force–depth and charge–depth nanoindentation response of several classes of anisotropic piezoelectric materials such as relaxor ferroelectrics for which analytical models are at present unavailable. Upon validating the finite element model for transversely isotropic materials, it is demonstrated that the nanoindentation response of anisotropic piezoelectric materials displays a strong dependence on the nature of the indenter geometry and relatively weak dependence on the indenter conductivity. Furthermore, by recourse to “longitudinal” and “transverse” indentations, the nanoindentation method can also be used to identify the poling directions in piezoelectric materials as well.     

Novel fabrication of bulk Al with gradient grain size distributions via powder metallurgy

We describe a novel approach to synthesize gradient microstructures, defined hereafter as containing a broad but continuous distribution of grain sizes. These microstructures extend the concept of a bimodal grain size distribution and the ability to design with multiple length scales. We demonstrate the proposed approach via experiments involving cryogenic ball milling of Al–4.5Mg–0.4Mn–0.05Fe and Al–50Mg powder followed by subsequent consolidation. Our results reveal that the grains in the consolidated powder present a gradient size distribution ranging from <100 nm to >3 μm. Moreover, phase composition analysis revealed a unique “interfingered” structure where the two starting phases were intermixed in a complex three-dimensional mesh. Hardness studies of this gradient microstructure show average Vickers hardness values of 200 ± 2.6, 204 ± 4.3 and 266 ± 50 for macrohardness, microhardness and nanoindentation, respectively. The standard deviation values highlight that the gradient microstructure is disordered locally, but homogenous macroscopically.     

Creep of micron-sized aluminium columns

Micron-sized aluminium columns, produced by focused-ion beam milling, were subjected to compressive creep in a nanoindentation machine using a flat-ended tip to study their time-dependent deformation behaviour at room temperature. At constant load, their strain increased almost linearly with time, with sporadic but large strain bursts superimposed. This represents a form of creep behaviour not known beforehand for aluminium. Strain bursts were also observed to occur during reloading at stresses higher than the first yield stress during initial loading.     

Reconstruction of Adoption Issues: Delineation of Five Phases Among Adult Adoptees

Five adoption‐reconstruction phases were identified in narratives of 100 adoptees ages 35 to 55 years. Phases ranged from no awareness of adoption issues (Phase 1) to acute awareness accompanied by anger, resentment, and sadness about adoption (Phase 3) to a sense of peace and acceptance (Phase 5). Consistent quantitative and qualitative differences were found among adoptees at the 5 phases on multiple measures of functioning.     

Deformation behaviour and 6H-LPSO structure formation at nanoindentation in lamellar high Nb containing TiAl alloy

Microstructure and deformation mechanisms at a nanoindentation in the lamellar colony of high Nb containing TiAl alloy have been studied using the focused ion beam and the transmission electron microscopy. Considerable deformation twins are observed around the nanoindentation, and a strain gradient is generated. A continuous change in the bending angle of the lamellar structure can be derived, and a strain-induced grain refinement process is observed as various active deformations split the γ grains into subgrains. In addition to all possible deformation mechanisms (ordinary dislocation, super-dislocation and deformation twining) activated due to the heavy plastic deformation, a 6-layer hexagonal (6H) long-period stacking ordered structure is identified for the first time near the contact zone and is thought to be closely related to the glide of partial dislocations.     

Validation of a phenomenological strain-gradient plasticity theory

Strain-gradient plasticity theories have been developed to account for the size effect in small-scale plasticity in metals. However, they remain of limited use in engineering, for example in standards for nanoindentation, because of their phenomenological nature. In particular, a key parameter, the characteristic length, can only be determined by fitting to experiment. Here, it is shown that the characteristic length in one such theory derives directly from known quantities through fundamental dislocation physics. This explains and validates the theory for use in engineering.     

Nanoindentation-induced elastic–plastic transition and size effect in α-Al2O3(0001)

The mechanical properties of α-Al₂O₃(0001) have been investigated using the technique of nanoindentation with a Berkovich indenter. Coupled with the Hertzian contact theory, a theoretical shear strength of 28?±?2?GPa was determined from the onset of pop-in events on load–displacement curves during loading, and the intrinsic hardness 30?±?3?GPa was obtained by analysis of the so-called indentation size effect, based on the concept of geometrically necessary dislocations. The predicted values of the shear strength, hardness and elastic modulus are in good agreement with available experimental data. The importance of experimentally calibrating the area function over the contact depth range prior to nanoindentation tests is emphasized.     

QUANTITATIVE AND/OR QUALITATIVE METHODS IN THE SCIENTIFIC STUDY OF RELIGION

Abstract. Qualitative research methods are essential to provide richness, but they are vulnerable to distortion of data by theory. The quantitative approach is necessary for the precision of hypothesis testing, but, by itself, this method is too critical to be creative. Religious studies should use both methods in alternate phases, with the qualitative approach creating new hypotheses and the quantitative approach critically testing them.     

Mechanical properties of nanocrystalline deformed layers induced by nanogrinding of CdZnTe single crystals

Nanocrystalline deformed layers were generated in cadmium zinc telluride (CZT) single crystals by nanogrinding using three different grit sizes. The mechanical properties of the deformed layers were measured using nanoindentation. The hardness of the deformed nanocrystalline layers in the soft-brittle CZT semiconductor was higher than that of the perfect single crystal. This result is different from those found for deformed layers of hard-brittle silicon semiconductors, where the hardness of the deformed layers is lower than those of the perfect single crystal.     

Repercussions of Transition Out of Elite Sport on Subjective Well-Being: A One-Year Study

This study examined the dynamics of subjective well-being during transition out of elite sport. French athletes (n = 16) retiring from sport following the Sydney Olympic Games were compared to active athletes (n =16) four times during the first year post-career termination using the 12-item General Health Questionnaire (Goldberg &Williams, 1988). Qualitative data from semi-structured interviews provided a complement to the quantitative data. Four phases were quantitatively identified in the evolution of subjective well-being, from an initial decrease, followed by an increase, a stabilization, and a final increase. Qualitative data demonstrated that the transitional athletes' feelings and attitudes during the transition ranged from initial difficulties facing the substantial changes in all life areas to reconstruction of and adjustment to a new life style and a new socio-professional situation. The importance for athletes to develop transferable skills during the sport career is underlined, as well as the potential for optimizing the timing and type of intervention/assistance offered during the specific phases of the transition and adjustment process following retirement from sport.     

The role of Improv in enhancement of Meaning in Life in youth: An explanatory sequential design

“A global mental health crisis” was sparked by the pandemic, especially for the youth as it exposed them to serious existential crises related to grief, loss, death and dying, deep psychological insecurities, etc. Additionally, this crisis came as a call for greater meaning in the personal and professional lives of youth. To deal with these issues in youth, Improv intervention is being used as an effective contemporary psychological technique to improve holistic perspective-taking. This pilot study investigated the efficacy of Improv intervention in enhancing Meaning in Life in youth using an explanatory sequential design. The sample comprised 80 youth (age range 18–25 years). The study was carried out in two phases—quantitative and qualitative. In the quantitative phase, a randomised control trial design was used to assess the efficacy of the intervention; this was followed by semistructured interviews to identify crucial themes that highlighted participants’ perceptions of Meaning in Life and the benefits of the intervention. Results revealed potential usefulness of Improv in Meaning enhancement.     

Intensive Transactional Analysis Psychotherapy (ITAP): A case series study

Intensive Transactional Analysis Psychotherapy (ITAP) is a new therapeutic approach based on the integration of Transactional Analysis and brief psychodynamic approaches. ITAP is based on two key therapeutic tools—the intrapsychic triangle and the interpersonal triangle—which the therapist uses to focus patients’ attention on moment‐by‐moment therapy processes. The aim of the present study was to provide early empirical documentation of ITAP effectiveness. To this aim, six patients (four females, two males) were longitudinally evaluated using an A‐B‐A mixed quantitative and qualitative design, with evaluations at Baseline, Treatment and Follow‐up phases. Each patient received 16 50‐min weekly sessions of ITAP therapy over 4 months. For quantitative evaluations, patients filled out the Clinical Outcome in Routine Evaluation‐Outcome Measure (CORE‐OM) at each evaluation. Effects size values were estimated to evaluate quantitative changes comparing mean scores of Baseline, Treatment and Follow‐up phases. At the first follow‐up, the Change Interview was used to qualitatively evaluate patients’ perceived changes. In the quantitative data, four of the six patients reported a very good outcome, with large to very large effect sizes in Baseline versus Treatment and/or Baseline versus Follow‐up scores comparisons, whereas two patients reported variable fluctuations within the non‐clinical range of outcome scores. In the qualitative evaluations, all patients reported several moderately to extremely important perceived changes attributed to psychotherapy.     

Development and Initial Validation of a General Psychological Well-being Scale (GPWS) in an African Context

This study aimed to develop and validate the General Psychological Well-being Scale (GPWS) in an African sample, based on the empirical overlap between hedonic and eudaimonic facets of well-being as found in previous research. The quantitative cross-sectional study was conducted in three phases: secondary data analysis (n = 2005), pilot study (n = 296) and main study (n = 459). The pilot and main study included the GPWS as well as other psychological well-being measures for criterion-related validity. The pilot study yielded satisfactory psychometric properties. The main study yielded a high, reliable Cronbach alpha of.89 and evidence of construct validity. The GPWS appears to be a unidimensional scale suitable for research use with Setswana-speaking people.     

A Review of Articles Using Observation Methods to Study Creativity in Education (1980–2018)

This paper reports on an integrative literature review of published articles that used either quantitative or qualitative observation methods to research creativity in learning contexts. Observation is an empirical research method used in quantitative and qualitative naturalistic studies focused on understanding behavior and interactions as they unfold in real-time, which makes it particularly salient for examining the processes associated with the generation and adoption of creative ideas. However, observation remains underutilized in the field of creativity studies, partly because data collection can be time and resource intensive, but also because there are a lack of protocols and recommended research practices for observing creative thinking and problem solving in an educational environment that covers all phases of design, collection, analysis, and reporting. Thirty-seven articles from 1980–2018 were reviewed along seven dimensions: definition of creativity, unit of observation, observer role, observation sampling method, research design, data collection, and data analysis. The paper concludes with five recommendations for using observation to advance the state of research on creativity and education.     

Die Entwicklung der Tötungsdelikte in Deutschland

Despite its low quantitative importance compared to total crime, the development of homicide is a fundamental indicator for crime-policy efficiency. A low crime rate has a significant positive effect on the quality of life. This article analyses the development of homicide on the basis of its registration by the Polizeiliche Kriminalstatistik (Police Crime Statistics) from 1953 to 2006. The development is not consistent. There are five phases where moderate increase, strong increase, stabilisation and decrease have to be differentiated. At present there is a phase of obvious decrease so that the current percentage of homicide corresponds to that at the end of the 1960ies. There is also a striking difference between attempted and accomplished offences. While the percentage of accomplished homicide was almost constant in the period mentioned, the percentage of attempted offences has meanwhile almost tripled and is twice as high compared to the situation in 1953.     

Nanoindentation measurements on deformation-induced α’-martensite in a metastable austenitic high-alloy CrMnNi steel

The hardness of deformation-induced α’- martensite and parent austenitic matrix in high-alloy CrMnNi steel was investigated by nanoindentation measurements inside scanning electron microscope using picoindenter. After the indentation, the microstructure was investigated by electron backscattered diffraction measurements. The hardness values for α’-martensite are only 24% higher than those of austenite. Thus, the increase in strength during the formation of deformation-induced α’-martensite is rather caused by the small grain size of α’-nuclei resulting in a dynamic Hall–Petch effect than by its “intrinsic” hardness.     

Crystallographic orientation dependence of nanoindentation hardness in austenitic phase of stainless steel

ABSTRACT

This paper presents the indentation hardness evolution in different in-plane directions of austenite grains whose {111} planes are parallel to the sample surface determined by nanoindentation tests and electron back scattering diffraction (EBSD) analysis. A scanning electron microscopy (SEM) image of the indentation surface around one of the indents indicated the activation of two sets of slip planes with respect to each of the three indenter surfaces for a Berkovich tip. The identification of the slip traces by EBSD data analysis is in accord with Schmid`s law. We therefore proposed a new approach for defining the orientation parameter to interpret the indentation hardness. The orientation parameter was shown to be the minimum value of the three maximum Schmid factors on the secondarily activated slip planes in three directions for a Berkovich tip. Indentation hardness increased with the decrease in the orientation parameter and was dependent on in-plane orientation.     

High-temperature nanoindentation behavior of Al/SiC multilayers

Nanoscale Al/SiC composite laminates have unique properties, such as high strength, high toughness, and damage tolerance. In this article, the high-temperature nanoindentation response of Al/SiC nanolaminates is explored from room temperature up to 300°C. Selected nanoindentations were analyzed postmortem using focused ion beam and transmission electron microscopy to ascertain the microstructural changes and the deformation mechanisms operating at high temperature.     

Onset of plasticity in a Σ = 5 GaAs compliant structure

Compliant structures have been fabricated in which a thin GaAs layer (thickness between 10 and 20nm) was bonded on top of a GaAs substrate with a large twist angle (about 37). This twist angle value was chosen so that the energy of the boundary (coincident boundary of type =5 (001)) was minimized. The structure of the interface was characterized and the onset of plasticity in such a compliant substructure was investigated using nanoindentation that allowed the low-load deformation regime to be observed. The results are compared with those obtained under the same conditions on a GaAs bulk substrate alone. No plastic zone was observed by transmission electron microscopy in the compliant structure under loads below 0.25mN while, under the same loads, plastic deformation was observed in the bulk substrate. For higher loads (2mN), plastic-flow enhancement was observed in the compliant structure. The results are discussed in the light of the arrangement of dislocations observed in the plastic zones.