Instytut Podstawowych Problemów Techniki

UMO-2019/35/B/ST8/03131

2020-06-22 / 2024-06-21

Jedyny wykonawca

NCN

OPUS

18

Experimental and numerical investigation of the effect of microstructure on the residual stresses, thermal and mechanical properties in aluminum-matrix graded composites (ALU-FGM) Research objectives/ hypotheses The general scientific objective of the proposed research project is to explore, through a carefully designed experimental program supported by microstructure-based numerical models the effects of material microstructure on: (i) processing-induced thermal residual stresses, (ii) thermal properties, and (iii) selected mechanical properties of Al2O3/AlSi12 and SiC/AlSi12 metal-matrix composites with composition gradient (FGMs). The effect of microstructure on the target properties will be examined by (i) considering two different types of ceramic reinforcement, Al2O3 and SiC, (ii) optimizing the process parameters (e.g. milling/pause times and speed), (iii) varying the volume fraction of ceramic reinforcement in composite layers, (iv) using different particle sizes of the ceramic powders, (v) employing two variants of sintering techniques (HP and SPS). The basic hypotheses of the project are: (1) particle size and type of ceramic reinforcement strongly affect the residual stress field, mechanical strength, fracture toughness and thermal conductivity of Al2O3/AlSi12 and SiC/AlSi12 composites, and (2) thermal residual stresses generally influence the strength, toughness andthermal conductivity of Al2O3/AlSi12 and SiC/AlSi12 composites, but for some microstructure morphologies other factors can outweigh the influence of TRS on these properties. Research methodology The proposed research methodology is a tangible example of the full “fabrication-characterization-modeling” approach which is nowadays often exercised in research projects on advanced materials. The microstructure of the graded composites fabricated by sintering will be characterized by advanced electron microscopy techniques (SEM/TEM) and X-ray micro-CT and synchrotron tomography. Thermal residual stresses in FGM layers will be measured by diffraction and optical techniques to unambiguously identify the effects of FGM structure and morphology on the residual stresses. Advanced numerical modeling tools (“micro-CT FEM”) making use of the actual material microstructure from the micro-CT images will be employed to create FE meshes when predicting thermal residual stresses, thermal conductivity and fracture toughness of the FGM as a function of the changing microstructure. Numerical models will be compared with the experimental results obtained within the project. These project objectives require an interdisciplinary research team with complementary expertise and skills in material science and engineering, mechanics of materials and numerical methods. Such a combination of expertise is provided by the researchers involved in this project. Consultations with an international expert on modeling of residual stresses and fracture of MMCs is planned. Expected impact of the research project on the development of science The project will generate a considerable amount of new knowledge in the field of thermal residual stresses and thermomechanical properties of aluminum-matrix graded composites. The use of micro-computed tomography to precisely mimic the complex microstructure when creating meshes for the FEM modeling of residual microstresses in the FGM layers belongs to the mainstream of scientific research in multi-component materials. The comprehensive set of information on the graded composites delivered by ALU-FGM will help answer the fundamental question of how the microstructure can alter the internal residual stresses and the selected macroscopic properties of FGMs. The results may have an impact on industry sectors seeking lightweight structural materials with good thermal conductivity, low level of internal residual stresses, low thermal expansion and high specific strength.