Literature Review.

studied. At higher temperatures the process of relaxation is quick and for times of one hour the properties of annealed powder were determined by initial powder properties and temperature of annealing.

POROSITY IN Ni-BASE ALLOY POWDERS

Y F Temovoi, N N Pasheteva, Poroskovaya Metallurgia, 1990, No 1,43-47, in Russian.

A model for formation of pores in powders is deduced from a study of forces which promote or prevent gas capture by the molten metal at different stages. It is concluded that gas capture is most probable at the stage when the melt flows from the jet. Effects of the various parameters (in atomization) on porosity are studied. Measures to control porosity in powders are suggested.

KINETICS OF DECOMPOSITION OF Ni-OXALATE BY HYDROGEN

N T Gladldkh, et al, Poroskovaya Metallurgia, 1990, No 1, 57-62, in Russian.

Decomposition of Ni-oxalate in flowing hydrogen was studied. Highly dispersed Ni powders were produced. Process variables were investigated and correlated with the powder characteristics.

PROPERTIES OF ELECTROLYTIC Cu POWDER

O A Potapov, et al, Poroskovaya Metallurgia, 1990, No 2, 1-8, in Russian.

Structure and properties of electrolytic Cu powder produced, from a sulphate electrolyte at constant potential have been examined. Surface morphology was studied by SEM.

STUDY OF PARAMETERS FOR CENTRIFUGAL ATOMIZATION OF MOLTEN ZINC

K Halada, H Sugo, J Japan Soc. Powder and Powder Metallurgy, Vol 37, No 3, 1990, 398-404, in Japanese.

Zn powders produced by centr i fugal atomization were characterized with respect to the measured variables of the process, size and

speed of rotation of the disc and flow rate of the molten zinc. Process monitored by IR thermography and CCTV. Shown that disc heating is required to ensure production of fine particles. Distribution of particles within the processing chamber also studied.

FLYING DISTANCE OF CENTRIFUGALLY ATOMIZED PARTICLES

K Halada, H Suga, J Japan Soc. Powder and Powder Metallurgy, Vol 37, No 3, 1990, 405-411, in Japanese.

Spatial distribution of particles atomized in a centrifuge was measured. It was shown that finer particles travelled greater distances than the coarse fractions. Calculated distances are double those measured. Possible reasons are suggested.

DISTRIBUTION OF LEAD IN AN AI ALLOY MADE BY CENTRIFUGAL ATOMIZATION (CA)

H S Kim, et al, (Hong Ik University, Seoul, Korea), J. Korean Inst. of Metals, Vol 28, No 4, 1990, 326-335, (in Korean).

Structure and microhardness of A1-5 and 10%Pb powder produced by CA was investigated by back scattered SEM. It was found that Pb was uniformly distributed in the powder particles. Conditions of CA varied and powders in range 20-600 ~ were produced.

MICROSTRUCTURE OF ULTRAFINE Fe POWDERS

S Wang, et al, (Academica Sinica, Shenyang, China), Acta Metallurgica Sinica B, (English Ed.) Vol 3, No 2, 1990, 136-139.

Constitution, structure and morphology of Fe powders produced by gas evaporation were examined by X-ray analysis, SEM and electron spectroscopy (ESCA). Particles were found to be spherical, 20 nm in diameter and coated with crystalline Fe304 nm thick.

WATER ATOMIZATION OF AI-5Cro2Zr-lMn

G Staniek, et al, (German Aerospace Establishment, Cologne, Germany), Powder Metallurgy Int., Vo122, No 4, 1990, 7-10.

The AI alloy has been water atomized to produce rapidly solidified metallic powder. In this work the stream of molten metal impinges on a rapidly spinning metal disc covered with a thin film of water. The resulting powder was dried and compacted by extrusion. The properties of the extruded material are compared with those of material produced from air and He atomized powder.

EFFECT OF HIGH RATE LOADING ON COMPACTION

O V Roman, et al, Poroskovaya Metallurgia, 1989, No 11, 14-19, in Russian.

A physical model of powder behaviour under high energy rate compaction is presented. The t rans i t ion from quas i - i sos ta t ic to non-equilibrium conditions is discussed. Consideration is given to the correlation between compaction mechanisms and production practice using different materials.

CONTACT INTERACTIONS BETWEEN Cu-Sn AND Cr-Ni ON HEATING

V G Delevi, et al, Poroskovaya Metallurgia, 1989, No 11, 56-59, in Russian.

Interaction between Cu-Sn and Cr-Ni on heating in vacuo at 780-800*C for 2-10 hours was studied. The mechanism of establishment of reaction zone is discussed. Possible app l ica t ions to format ion of diamond-multicomponent matrix materials are outlined.

SINTERING OF Fe IN A VARIABLE MAGNETIC FIELD

Y U Boiko, et al, Poroskovaya Metallurgia, 1989, No 12, 14--18, in Russian.

It is shown that a magnetic field of frequency 1 Hz and intensity 1000 Oe activates the initial stage of sintering corresponding to dislocation mass transfer. Theoretical analysis and experiment lead to the conclusion that the effect results from magneto-elastic interaction with domain boundaries.

718 MPR October 1990