Abstract: To provide a hydrogen storage alloy usable as a negative electrode having a long life and good high-discharge characteristics. Hydrogen storage alloy for cell wherein its general expression is as follows:RNi.sub.a Co.sub.b Al.sub.c Mn.sub.d Fe.sub.e(where R is a mixture of rare earth elements and contains 25.about.75 wt. % La; 3.7.ltoreq.a.ltoreq.4.0, 0.1.ltoreq.b.ltoreq.0.4, 0.20.ltoreq.c.ltoreq.0.4, 0.30.ltoreq.d.ltoreq.0.45, 0.2.ltoreq.e.ltoreq.0.4, 0.5.ltoreq.b+c.ltoreq.0.7, and 5.0.ltoreq.a+b+c+d+e.ltoreq.5.0).

Abstract: High-purity metallic chromium is produced by a method of initially preparing a mixture of chromium oxide, aluminum, carbon and an easily sulfidable metallic powder, and subsequently providing a thermite-reaction with the mixture to produce thermite-crude metallic chromium and a solid solution of carbon and easily sulfidable metal. Residual impurities in the thermite-crude metallic chromium are subsequently removed by heat treating the crude metallic chromium. This method produces high-purity metallic chromium advantageous for preparing corrosion and heat resistant chromium-containing alloys.

Abstract: A material for storage of hydrogen, consisting essentially of an alloy represented by the following general formula:LmNiawhere Lm signifies rare earth metals which contain 40 to 70% by weight of lanthanum, 0.1 to 20% by weight of cerium and other metals such as neodymium, praseodymium, and/or samarium; and a signifies a range of 4.8<a<5.5. Thus, improved hydrogen absorption under relatively low pressure at room temperatures and also improved hydrogen absorption pressure and release equilibrium pressure can be provided.

Abstract: A fuel tank for a hydrogen vehicle in which a plurality of fuel cylinders are disposed and contained in a casing of the fuel tank for containing hydrogen storage alloy, the fuel cylinders are connected to a header mounted integrally with the casing for containing the fuel cylinders, a conduit for supplying engine exhaust gas is connected to the casing for externally heating the fuel cylinders in the casing.