Material Science & Physics Sessions

Title: Microstructure Studies of Additive Manufacturing

Additive manufacturing is an opportunity for the energy field to produce sophisticated geometries. However, there are still several roadblocks to its use to make a wide variety of parts. One needs to demonstrate that parts produced with conventional processing routes can be substituted by parts fabricated by additive manufacturing. The objective of this work is to shed light on the microstructure-mechanical property relationships of two types of materials : 316L austenitic stainless steel produced by laser powder bed fusion (L-PBF)and superalloys. In 316L, one specific powder leads to a finer grain structure that goes along with texture randomization. The underlying mechanism responsible for grain refinement and texture randomization will be discussed and can be considered as an alloy design strategy in the framework of additive manufacturing. In superalloys, induced segregations and precipitations are studied at nanometer scale to explain hot cracking observed in some alloys.

Title: AM Research at McMaster: Processing and Properties

Title: High-throughput investigations of phase transformations in multi-component alloys : combinatorial experiments and machine learning 

The assessment of compositional effects on phase transformations and their kinetics is a labor-intensive and time-consuming endeavor when using discrete-composition samples, in terms of both the preparation and the experiments themselves. Such a task can be greatly accelerated using a combinatorial methodology based on the combination of compositionally graded samples with in situ time- and space-resolved synchrotron diffraction. This methodology will be illustrated through its recent successful application to the austenite-to-ferrite transformation. The unprecedented amount of data that was collected provides some long awaited insight into the mechanism of this transformation when it happens with negligible partitioning of substitutional elements and is well-suited to machine learning modeling approaches.

Title: Accelerated Material Discovery Platforms

Title:Magnetic materials for energy conversion

Increasing energy consumption and greenhouse gas emission has triggered extensive research on energy conversion materials. Our investigations are focused on intermetallic materials for magnetic refrigeration on one hand and permanent magnets applications on the other hand.

Magnetocaloric effect and magnetic refrigeration

Replacing conventional vapor-based refrigeration (15% of the total energy generated worldwide) with  magnetic refrigeration (solid state) is the goal. Magnetic refrigeration is based on the magnetocaloric effect that is a change in temperature and/or entropy of a material upon application of a magnetic field.

Our goal  is to design and discover new MC materials with properties, notably changes in isothermal entropy and adiabatic temperature, superior to current systems. This requires a mastering of the interplay between structural and magnetic properties. Examples of our current investigations will be presented on the following intermetallic compounds.

1- magnetostructural properties of model Laves compounds (AFe2 systems) and extended to new intermetallic phases to be synthesized in the frame of an exploratory research approach seeking for high performance materials for magnetocaloric applications or hard magnetic phases. Magnetically and structurally tunable AFe2 systems are of particular interest as potential magnetocaloric materials.

2- La(Fe,Si)13 –type compounds . The Curie temperatures of La0.7Ce0.3Fe13-x–yMnxSiy compounds that are hydrogenated to saturation can be raised to near room temperature and adjusted to the desired working temperature by regulating Mn content based on the linear relationship between TC and Mn content.  Neutron diffraction reveals the preferential occupancy of Mn atoms. The giant magnetocaloric effect, linearly adjustable TC, and excellent age stability make the La0.7Ce0.3Fe11.55-yMnySi1.45 hydrides be one of the ideal candidates for room temperature magnetic refrigerants.

Hard ferromagnetic materials

Hard ferromagnetic materials with high remanent magnetization (permanent magnets) are of great industrial and household importance, since those are key components of electric generator systems. Efforts are made to discover and study yet different magnetic materials in various related R-M-B (R = rare-earth metals and M = transitions metals) systems. Our investigations aim at performing both targeted and exploratory research in the R-M-B systems for a search of novel ferromagnetic materials with applications as highly performant and accessible permanent magnets. Results will be presented on the R-M-B/C systems in which addition of light and non-magnetic B atoms introduces additional structural complexity which, in turn, can yield formation of compounds with different magnetic properties. One example is the Rn+1Co3n+5B2n system (CaCu5-type structure, P6/mmm) for which different n values yield distinct phases: RCo4B for n = 1; R3Co11B4 for n = 2; R2Co7B3 for n = 3 and RCo3B2 for n = ∞.

Title: Characterization of Advanced Functional and Energy Materials

Title: Dynamic fracture, very high loading rates, tests under vacuum

In the present work the tensile strength of ceramics is investigated based on shockless plate-impact spalling test. The Target made of a buffer plate as front face and ceramic plate as backing is impacted by a wavy-machined flyer plate allowing the wave front to be smoothed to obtain strain-rate ranging from 9,000 to 30,000 s-1. Based on these experimental data, the strain-rate sensitivity of ceramics is deduced.

Title: Biological Tissues and Biomaterials

Bone diseases require increasingly complex diagnosis for efficient treatment. There is growing evidence that multiscale structural characteristics of the mineralized tissue need to be considered for such diagnosis and to better understand the fundamental pathological processes. We will show how the potential offered by the specific expertise in bone nanoscale analysis using the electron microscopy infrastructure of the CCEM at McMaster, combined to this acquired using synchrotron radiation and optical microscopy at UGA provide a unique framework for such purposes.

Highlights presentation of biomedical research and collaboration at University of Tokyo.

Highlights presentation of materials science research and collaboration at University of Tokyo.

Highlights presentation of nuclear research and collaboration at University of Tokyo.

Highlights presentation of research and collaboration at Universities of Toronto and Tokyo.

Title: Electrohydrodynamic enhancement of heat transfer in dielectric fluids  

Electrohydrodynamic is the multiphysic coupling between electric fields and fluid flows. When imposing an electric field within a media using external electrodes, one can actively enhance processes by modifying the flows involved. Grenoble and McMaster are places where this physics has been foreseen for decades as a means of heat transfer enhancement. After giving a brief overview of the state of the art, recent developments done at Grenoble on the EHD enhancement of two-phase heat transport devices and on single phase EHD convection will be presented.

Title: Sustainability in High Temperature Process Metallurgy

Title: Presentation of the experimental platform Coriolis

I will present the Coriolis platform at LEGI, Grenoble, measuring 13 m in diameter, is the largest rotating platform in the world dedicated to fluid mechanics. Its main activity is the experimental modeling of geophysical flows, taking into account the rotation of the Earth, the density stratification and the topography. The large dimensions allow to approach the inertial regimes that characterize the ocean/atmospheric dynamics, with a weak influence of viscosity and centrifugal force. The realized laboratory experiments allow to test the ocean/atmospehric dynamics models and to develop their physical parametrizations, crucial for reliable prediction of ocean and climate models.

Examples of realized projects will be presented too.

Title: Computational Materials Engineering

Title: Interaction between cracking and microstructure: examples and comments on fracture models

We illustrate the interaction between fracture and microstructure by presenting a study devoted to the estimation of durability of plasma spray coatings. The influence of the processing, environment and load level. A multi-scale approach is adopted in which the inter-splat and intra-splat crack growth is described with a rate- temperature and humidity dependent cohesive zone model that mechanically represents the reaction-rupture mechanism underlying stress and environmentally assisted sub-critical failure. It is found that the relaxation of the initial thermal stresses generates a significant initial damage at the inter-splat scale by the nucleation of inter-splat cracks and a minor initial damage at the intra-splat scale. The results show that the rate of inter-splat cracks increases with the relative humidity and especially with the temperature at which the relaxation occurs. The effect of the initial damage generated by the thermal aging on the resistance of the polycrystal of plasma sprayed zirconia against intra-splat slow crack growth under static fatigue loading is investigated. The results show that the initial damage at the intra-splat scale does not affect its resistance against intra-splat slow crack growth. However, the initial damage at the inter-splat scale leads to an increase in the slow cracking rate for a loading level KI and a reduction in the threshold load K0 below which no slow crack growth occurs as the individual splat is embedded in a damaged equivalent continuum representing the overall splat structure. The aim of this work is to provide a reliable predictions and insight in long lasting applications of plasma sprayed ceramic materials.

Reference: B El Zoghbi, R Estevez, Surface and Coatings Technology, 438, 128379.