Naoyuki Kanetake

Fabrication and mechanical properties of in situ formed carbide particulate reinforced aluminium composite

Stable carbide particles of TiC, ZrC and TaC were in situ synthesized in liquid aluminium by the reaction between Al-Ti, Al-Zr or Al-Ta systems liquid alloy and SiC or Al4C3 particles. It was possible to generate TiC particles of nearly 1 μm diameter, even utilizing SiC of 14 μm. However, the dispersion behaviour of TiC particles in the matrix depended on the size of the raw carbide. Finer SiC made the dispersion of TiC particles more uniform, resulting in a greater improvement of the mechanical properties. Furthermore, although Al-Ti-Si system intermetallic compound was detected in a TiCp/Al-Si composite fabricated by the melt-stirring method, those compounds considerably decreased in the composite fabricated by the in situ method. The mechanical properties of in situ formed TiCp/Al-5 wt% Mg and TiCp/Al-5 wt% Cu composites were better than those fabricated by the melt-stirring method and by T6 heat treatment, the properties of in situ formed TiCp/Al-5 wt% Cu composite were further improved. The experimental results were analysed by the reaction model based on the assumption that the overall reaction rate was controlled by both the reaction and the diffusion.

Processing of Intermetallic Foam by Combustion Reaction

Intermetallic (Ni–Al) foams were fabricated by combustion reactions. The heats of formations of these intermetallics were high enough to obtain bulk reaction products and pores were formed in the specimen during the combustion reaction. Some processing parameters of the combustion reaction were varied to control porosity and cell morphology of the intermetallic foams. The amount of aluminum in the green compact was an important factor in controlling the porosity of the synthesized nickel aluminide. The relative density of the green compact needed to be more than 0.72 for effective foam formation. The enthalpy change of the combustion reaction was controlled either by adding a reaction- enhancing agent (B4C) or by adding a heat-absorbing agent (TiC). Both the porosity and the cell size of the synthesized intermetallics were successfully controlled by changing the reaction enthalpy (from 10 to 85 % porosity).

Calculations from texture of earing in deep drawing for FCC metal sheets

Abstract The present study aims to calculate the height at each peripheral position of a cup drawn from polycrystalline sheet using texture data. In the analytical treatment the polycrystalline sheet is simplified to an aggregation of many single crystals with various orientations, and the texture is represented by a three-dimensional crystallite orientation distribution function. The ear is calculated crystallographically using the orientation distribution function as a volume fraction of a certain oriented crystal. In the experiment aluminium, Al-Mg alloy and copper sheets which are treated under various conditions of cold rolling and heat treatment are used. The average textures over the thicknesses of the sheets are measured by the Schulz reflection method. The calculated ears based on the measured textures are compared with the experimental ears for each material. The results show that all the principal features of the ears of drawn cups are predicted satisfactorily by the calculation.

Superplasticity in Mg–Li–Zn Alloys Processed by High Ratio Extrusion

Superplastic behavior of Mg-8.5Li-1Zn and Mg-8.5Li-3Zn alloys has been investigated. Dynamic recrystallization occurs in the Mg–Li–Zn alloys during extruding with high ratio after stir casting. Mg-8.5Li-1Zn alloy exhibits an elongation of about 400% at the high strain rate of 1.1 × 10−2 S−1 at 623 K, while the Mg-8.5Li-3Zn alloy shows maximum elongation of more than 540%. The apparent activation energy for superplastic flow of both Mg-8.5Li-1Zn and Mg-8.5Li-3Zn alloys at 573–673 K is about 86 kJ/mol and 79 kJ/mol, respectively, so that the dominant deformation mechanism in Mg–Li–Zn alloys is grain boundary sliding (GBS) controlled by grain boundary diffusion.

Combustion Synthesis of Porous TiC/Ti Composite by a Self-Propagating Mode

Porous titanium carbide (TiC) and TiC/Ti composites were synthesized by self-propagating high-temperature synthesis (SHS). Titanium and carbon powders were blended by various Ti/C blending ratios. The heat of reaction between titanium and carbon was high enough to induce the self-sustaining reaction of TiC formation on condition that some processing parameters (Ti/C ratio and porosity of the precursor) were appropriately selected. When the Ti/C blending ratio was high, the excess amount of titanium absorbed the heat of reaction. Consequently, the heated zone was not heated up to the ignition temperature. On the other hand, when the Ti/C ratio was low, high thermal conductivity of the precursor prevented an ignition of the heated side of precursors. The pore morphology was controlled by changing the Ti/C ratio and the preheat temperature.

Effect of alloying elements in the brazing sheet on the bonding strength between Al2O3 and aluminum

Ceramics have several outstanding mechanical properties especially at high temperatures, but a difficulty in machining has been hindering the cost-effective use. Hence, bonding between ceramics and metals has become an important technology. Among many bonding techniques such as brazing, diffusion bonding, frictional bonding and so forth, brazing is one of the most promising methods for practical applications. There are several bonding parameters such as temperature, time, pressure and atmosphere. In this work, Al{sub 2}O{sub 3}/aluminum bonding using an aluminum alloy as a filler sheet is dealt with, and the effects of some parameters on the bonding strength are mainly discussed.

Calculations of earing in deep drawing for BCC metal sheets using texture data

Abstract The present study aims to calculate the height at each peripheral position of a cup drawn from a polycrystalline BCC metal sheet using texture data. In an analytical treatment, the polycrystalline sheet is simplified by considering it to be an aggregate of many single crystals with various orientations. A three-dimensional crystalline orientation distribution function which is constructed from measured texture data is used as the volume fraction of a particular oriented crystal. The ear is calculated crystallographically by considering both restricted glide and pencil glide. In an experiment four kinds of steel sheets were used. An average texture over a thickness of the sheet was measured by the Schulz reflection method. The calculated ear based on the measured texture was compared with the experimental ear for each sheet. The results show that all principal features of the ear of the drawn cup are predicted satisfactorily by the calculation in which pencil glide is not taken into consideration.

Microstructure refinement of Al-Si alloy using compressive torsion processing

A Compressive Torsion Processing (CTP) is a unique severe plastic deformation process which can easily apply very large strain without shape change to a work piece. Hypereutectic Al-Si alloys have good properties such as low thermal expansion and high wear resistance. It is important for the alloys to control the size of second phase particles (primary and eutectic silicon, intermetallic compounds) as well as grain size of aluminum matrix. In the present work, the CTP was applied to hypereutectic Al-Si alloy (AA390) to investigate the possibility of microstructure refinement of the alloy and the mechanical property of processed alloy was also investigated by tensile test.

Crystallographical Calculation of Earing in Deep Drawing under Various Conditions

Earing in the cup drawing of sheet metals is calculated quantitatively using a crystallographical theory with measured texture data. In the analysis a polycrystalline sheet is simplified to be an aggregate of many single crystals with various orientations, and a crystallite orientation distribution function which is calculated from the measured texture is used as a volume fraction of a certain oriented crystal. The circumferential distribution of radial strain in a flange of a blank being drawn is calculated by considering a restricted glide in a crystal, and then cup height at each peripheral position of a drawn cup is calculated from this distribution of radial strain. For an aluminium, a copper and two steel sheets the calculated cup profiles are compared with experimental ones under various drawing conditions of dimension of a punch, a die and a blank. The result shows that earing in the drawn cup can be predicted satisfactorily by the present calculation for a wide range of drawing conditions and materials.

Effect of Elemental Powder Size on Foaming Behavior of NiTi Alloy Made by Combustion Synthesis

Nickel titanium (NiTi) foams were made by combustion synthesis of powders with the help of ZrH2 as foaming agent and TiB2 as endothermic agent. In this paper, we investigated the effect of elemental powder size on the foaming. The powder size of Ni and Ti affected the ignition temperature of the combustion reaction, cell morphology and microstructure of the foams. The cell morphology of the foams was also modified by the powder size of TiB2.