Hiroshi Saikawa

Structure and mechanical properties of internally hydrided Mg-IIIa transition metal alloys

Magnesium alloys containing IIIa transition metals, such as Sc, Y and Ho, respectively, were hydrogenated at 773 K and examined for microstructure, X-ray diffraction pattern, micro-Vickers hardness, and tensile properties at room and high temperatures. Results obtained are as follows:1.The alloys, respectively, have been internally hydrided and have precipitated hydrides of the IIIa transition metals as small flake-like particles in the matrix and at grain boundaries, as well as twin boundaries.2.The dispersed hydride particles do not necessarily contribute to further hardening of the alloys at room temperature and up to near 673 K.3.However, the dispersed particles are very stable and seem to improve mechanical properties of the alloys above 673 K.4.Presumed relationships of crystallographic coincidence between the matrix and hydrides have been obtained.

Special issue "Magnesium and magnesium alloys". Preparation of porous sintered compacts by mixing magnesium powder in the green state.

Being mixed with magnesium powder by up to 50%, 304 stainless steel and titanium powders were compacted under various compacting loads, respectively, and then the green compacts were sintered in a vacuum of 10-2Pa, finally at 1375K where magnesium can be vaporized completely. The sintered compacts were examined as to density, compressive strength and structure. The density and compressive strength decreased with increase in the amount of magnesium powder added to the green compacts, as well as decrease in the compacting load. The process was applied to make sintered ZrNi compacts capsulated with porous sintered stainless steel compacts. Sintered titanium and nickel compacts with a graded porosity distribution were also prepared, respectively.

Work hardening of aluminium bicrystals

Analyse de la distribution de la durete Vickers dans deux bicristaux lamines a temperature ambiante, 423 K et 573 K dans des directions differentes