Abstract: Disclosed herein is an aluminum matrix composite powder comprising 1 to 40% by weight of ceramic particles dispersed in a matrix of aluminum-silicon alloy. The matrix of the composite may further comprise at least one of Cu, Mg and transition metals.The aluminum matrix composite is prepared by a rapid solidification.In the aluminum matrix composite, the ceramic particles are very uniformly dispersed in the matrix, thereby the improvement of mechanical properties of product prepared therefrom can be obtained.

Abstract: A hypereutectic aluminum-silicon alloy produced by a powder metallurgy technique disclosed herein comprises 12 to 50% by weight of silicon, 1.0 to 5.0% by weight of copper and 0.01 to 0.05% by weight of phosphorus, the content of Ca as an impurity being controlled to be 0.03% by weight or less. The hyereutectic aluminum-silicon alloy of the present invention is excellent in machinability and mechanical strength.

Abstract: A hyper-eutectic aluminum-silicon powder containing extremely fine primary crystal silicon, is prepared by atomizing. First, a molten metal of a hyper-eutectic aluminum-silicon alloy containing phosphorus is prepared. This molten metal or melt is atomized with air or an inert gas and quench-solidified. Aluminum-silicon alloy powder containing primary crystal silicon of not more than 10 .mu.m in crystal grain size is obtained. This aluminum-silicon alloy powder contains at least 12 percent by weight and not more than 50 percent by weight of silicon and at least 0.0005 percent by weight and not more than 0.1 percent by weight of phosphorus. When this hyper-eutectic aluminum-silicon alloy powder is employed, it is possible to prepare a consolidate of powder which has improved mechanical properties, and provides a high yield.

Abstract: Disclosed herein is an aluminum nitride powder having the improved water-resistance, which is obtained by treating the aluminum nitride powder with an inorganic or organic phosphoric acid compound followed by heating at about 150.degree. to 800.degree. C. when the organic phosphoric acid compound is used.

Abstract: An apparatus for detecting leakage of water molecules through a defective portion, if any, of a container which comprises a vessel having a flange at the periphery thereof and a lid heat sealed to said flange and is filled with water-contained materials, such as foodstuffs, thereby detecting said defective portion, said apparatus comprising a chamber for receiving said container such that an enclosed space is formed along and in the vicinity of said sealed flange portion, partitions provided on said chamber for partitioning said enclosed space into a plurality of enclosed space cells, a plurality of humidity sensitive devices each provided individually associated with said enclosed space cells, a vacuum tank connected to said enclosed space cells for exhausting the air therefrom, a vacuum pump connected to said vacuum tank, and an electric circuit connected to said humidity sensitive devices for threshold detecting the outputs therefrom.