Tying Processing Parameters to the Microstructure and Mechanical Properties of Nanostructured FeNiZr Consolidated via the Field Assisted Sintering Technique

An oxide-dispersion-strengthened (ODS) nanostructured FeNiZr alloy was fabricated via high energy mechanical alloying, and subsequently consolidated by the field assisted sintering technique (FAST). A range of input parameters: Temperature, hold time and pressure were evaluated in an effort to optimize the mechanical response of the material. Improvements in density, up to 98.6% of theoretical, were observed with increasing consolidation temperature and hold time at the cost of decreasing hardness values resulting from microstructural coarsening. Hardness values decreased from 650 to 275 HV by increasing processing temperatures from 750 to 1100 °C. The relationships between the varied processing parameters, microstructure and the experimentally measured yield and ultimate tensile strengths are discussed. Specifically, the effect of varying the temperature and hold time on the resulting porosity, as observed via scanning electron microscopy (SEM) in tensile and compression samples, is emphasized.

Polylactic acid (PLA) based green composites reinforced pineapple leaf fibres: evaluation of processing and tensile performance

This paper reports on a study of the compression moulding and the vacuum forming of unidirectional pineapple leaf fibres/polylactic acid composites and the influence of process variables on the tensile properties of the material. The characterisation of the micro and meso structures of the pineapple leaf fibres is reported. The effect of consolidation temperature on the fibre thermal stability and the tensile properties of the composites is investigated. The results show that vacuum forming was found to be preferable process with high stiffness modulus and UTS of the composites, compared to compression moulding. The insignificant detrimental effect of 165°C high consolidation temperature was observed. Finally, the fibre thermal degradation seems to dominate the composite tensile performance over its interfacial quality between the fibre and the matrix.

FRICTION AND WEAR OF BULK NANOCOMPOSITE MATERIALS AlMg2/GRAPHITE

Consolidation of nanocomposite AlMg2/graphite powders, produced by mechanical synthesis in a planetary ball mill, was carried out. Using the methods of Raman spectroscopy, and X-ray diffraction analysis, the structural-phase composition of the obtained bulk materials was studied. It was found that the samples have nanocomposite structure consisting of nanocrystalline aluminum and nanosized graphite particles. An increase in the consolidation temperature up to 450 °C leads to the formation of a dispersed phase of aluminum carbide. The effect of graphite percentage and consolidation conditions on the microhardness was estimated. Mechanisms of bulk material hardening are determined. Tribological tests of the obtained nanocomposite materials under conditions of contact interaction with 4Kh5MFS steel at a load of 1–10 N were carried out. Data on the change in the friction coefficient and magnitude of mass wear depending on the consolidation conditions and the graphite content were obtained.

Three-dimensional orthogonal nonwoven single polymer composite

This paper describes the production and bending properties of three-dimensional orthogonal single polymer composites made from axial–braider commingling yarns where the braider yarns are completely melted to produce the matrix phase. The research was demonstrated using poly(lactic acid) yarn as an example. The optimum linear density ratio of braider and axial yarn was prescreened. The effects of consolidation temperature, pressure, and preform thickness on the bending properties were investigated by Environment Scanning Electron Microscope (ESEM) observations and mechanical bending tests. The results showed that the best bending properties of single poly(lactic acid) composite were detected in the braider–axial yarns ratio of 5/6. At this ratio, the increase of the consolidation temperature was to improve the bending properties (from 145 to 160℃), while it markedly decreased at 165℃. As the processing pressure increased, a remarkable improvement in the interfacial bonding between fibers and matrix occurred at a pressure of around 8 MPa. The increase of preform thickness gave rise to higher fiber volume fraction in the single poly(lactic acid) composite, with the result that the peak values of maximum stress and modulus were obtained at the preform thickness of 9 mm.