Multinational enterprises, industry 4.0 and sustainability:A multidisciplinary review and research agenda

Humanity is facing important challenges in the area of sustainability, for which all parties and means need to be brought together. Multinational enterprises (MNEs) are considered key actors for helping realise a successful transition towards a greener and more equitable future, in a time and age where much hope is set on novel digital technologies (often termed Industry 4.0) to expedite change ‘for good’. Despite this attention, however, there is limited insight into the actual state of the art regarding MNEs, Industry 4.0 and the implications for sustainability. As a result, academic knowledge of how MNEs develop and employ digital technologies, and what significance this has in relation to sustainability, is fragmented along disciplinary boundaries. We therefore conduct a systemic multidisciplinary review of the literature, examining the different types of digital technologies, the geographical scope of the studies, and the sustainability dimensions covered. Based on this critical evaluation, which considers both (potential) positive and negative implications, we present a promising research agenda for scholars on themes that are also highly relevant for organizations, individuals, societies and the planet

BCC-FCC interfacial effects on plasticity and strengthening mechanisms in high entropy alloys

Al0.7CoCrFeNi high entropy alloy (HEA) with a microstructure comprising strain free face-centered cubic (FCC) grains and strongly deformed sub-structured body centered cubic (BCC) grains was subjected to correlative nanoindentation testing, orientation imaging microscopy and local residual stress analysis. Depending on the geometry of BCC-FCC interface, certain boundaries indicated appearance of additional yield excursions apart from the typically observed elastic to plastic displacement burst. The role of interfacial strengthening mechanisms is quantified for small scale deformation across BCC-FCC interphase boundaries. An overall interfacial strengthening of the order of 4GPa was estimated for BCC-FCC interfaces in HEAs. The influence of image forces due to the presence of a BCC-FCC interface is quantified and correlated to the observed local stress and hardness gradients in both the BCC and FCC grains

Spherulitic and rotational crystal growth of Quartz thin films

To obtain crystalline thin films of alpha-Quartz represents a challenge due to the tendency for the material towards spherulitic growth. Thus, understanding the mechanisms that give rise to spherulitic growth can help regulate the growth process. Here the spherulitic type of 2D crystal growth in thin amorphous Quartz films was analyzed by electron back-scatter diffraction (EBSD). EBSD was used to measure the size, orientation, and rotation of crystallographic grains in polycrystalline SiO(2) and GeO(2) thin films with high spatial resolution. Individual spherulitic Quartz crystal colonies contain primary and secondary single crystal fibers, which grow radially from the colony center towards its edge, and fill a near circular crystalline area completely. During their growth, individual fibers form so-called rotational crystals, when some lattice planes are continuously bent. The directions of the lattice rotation axes in the fibers were determined by an enhanced analysis of EBSD data. A possible mechanism, including the generation of the particular type of dislocation(s), is suggested

In Situ Digital Image Correlation Observations of Laser Forming

In this study experimental and modelling methods are used to examine the microstructural and bending responses of laser-formed commercially pure titanium grade 2. The in situ bending angle response is measured for different processing parameters utilizing 3D digital image correlation. The microstructural changes are observed using electron backscatter diffraction. Finite element modelling is used to analyse the heat transfer and temperature field inside the material. It has been proven that the laser bending process is not only controlled by processing parameters such as laser power and laser beam scanning speed, but also by surface absorption. Grain size appears to have no influence on the final bending angle, however, sandblasted samples showed a considerably higher final bending angle. Experimental and simulation results suggest that the laser power has a larger influence on the final bending angle than that of the laser transverse speed. The microstructure of the laser heat-affected zone consists of small refined grains at the top layer followed by large elongated grains. Deformation mechanisms such as slip and twinning were observed in the heat-affected zone, where their distribution depends on particular processing parameters

Depth Profile Analysis of Thin Oxide Layers on Polycrystalline Fe–Cr

Surfaces of polycrystalline ferritic Fe–Cr steel with grain sizes of about 13 µ m in diameter were investigated with surface sensitive techniques. Thin oxide layers, with a maximum thickness of about 100 nm, were grown by oxidation in air at temperatures up to 450°C and were subsequently characterized using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and atomic force microscopy. Correlative microscopy was applied, which allows for element-specific depth profiles on selected grains with a particular crystal orientation. A strong correlation between the grain orientation and the thickness of the oxide layer was found. The sequence in the oxidation growth rate of ferritic Fe–Cr steel crystal planes is found to be {011} > {111} > {001}, which is unexpectedly opposed to known Fe-based systems. Moreover, for the first time, the Cr/Fe ratio throughout the oxide layer has been determined per grain orientation. A clear order from high to low of {001} > {111} > {011} was detected

Crystallization of GeO2 thin films into α-quartz: From spherulites to single crystals

Piezoelectric quartz (SiO2) crystals are widely used in industry as oscillators. As a natural mineral, quartz and its relevant silicates are also of interest in geoscience and mineralogy. However, the nucleation and growth of quartz crystals are difficult to control and not fully understood. Here we report successful solid-state crystallization of thin film of amorphous GeO2 into quartz on various substrates, including Al2O3, MgAl2O4, MgO, LaAlO3 and SrTiO3. At relatively low annealing temperatures, the crystallization process is spherulitic: with fibers growing radially from the nucleation centers and the crystal lattice rotating along the growth direction with a linear dependence between the rotation angle and the distance to the core. For increasingly higher annealing temperatures, quartz crystals begin to form. The edges of the sample play an important role in facilitating nucleation followed by growth sweeping inward until the whole film is crystallized. Control of the growth allows single crystalline quartz to be synthesized, with crystal sizes of hundreds of microns achieved on sapphire substrates, which is promising for further piezoelectric applications. Our study reveals the complexity of the nucleation and growth process of quartz and provides insight for further studies

Experimental determination and theoretical analysis of local residual stress at grain scale

Grain/phase boundaries contribute significantly to build up of residual stresses, owing to varied plastic/thermal response of different grain orientations or phases during thermomechanical treatment. Hence, accurate quantification of such local scale stress gradients in commercial components is important in understanding their mechanical performance. The current work introduces a correlative method utilizing Electron Back Scattered Diffraction and Focused Ion Beam-Digital Image slit milling methodology to accurately determine spatially resolved stress profiles in the vicinity of grain boundaries using commercially pure titanium as a model material. Measured local stress gradients were in good agreement with local misorientation values. The role of dislocation-grain boundary interactions on buildup of local stress gradients is elucidated. Stress profiles near grain boundaries initially display non Hall-Petch characteristics, followed by a typical Hall-Petch type variation of “one over square root of distance”. The observed trends allude to local stress relaxation mechanisms very close to the grain boundaries. The findings indicate that grain scale stress gradients can be significant in terms of playing a crucial role in macroscopic fatigue behavior