Phase formation during reactive sintering of powders

grain growth. Removal of the pressure resulted in rapid grain growth. The restriction of grain growth was attributed to an effect similar to the addition of grain growth inhibitors.

formation was studied by differential thermal analysis. The rate of heating was reported not to affect the proportions of the phases formed. TiB formed before the synthesis of TiBa.

EFFECT OF COMPACTION PRESSURE AND ATMOSPHERE ON SINTERING OF NANOMETRIC IRON POWDERS

design and tool materials

J. Bigot et al (CRNS, Vitry sur Seine, France). Shrinkage of nm sized Fe powders, consolidated at two pressures and sintered in diferent atmospheres, was compared with shrinkage in urn sized powders. From experimental data diffusion coefficient and activation energy were calculated for mass transport. NANOCOMPOSITES OF METALS AND REFRACTORY COMPOUNDS PROCESSED BY MECHANICAL ALLOYING H. Kubsch, B.F. Kieback. (Fraunhofer Inst., Dresden, Germany). Effectiveness of MA in the synthesis of intermetallic compounds from elemental powders was discussed for binary and with reference to ternary mixtures, nitrides, carbides and borides of Ti, Zr, Nb and V with Fe or Ni as the ternary element. Generation of the hard phases was reported to be a three-stage process. PREPARATION OF ALUMINA BASED NANOCERMETS BY REACTIVE MILLING AND HOT ISOSTATIC PRESSING

Tool

INTELLIGENT PM COMPONENT AND TOOLING DESIGN SYSTEM D.C. Zenger et al (Worcester Polytechnic Inst. USA). Progress in the development of an automated part and tooling design system was outlined. The system incorporates computer aided design techniques with a knowledge of PM tooling and part designs and process data. Working drawings of tooling elements, which can be modified to meet manufacturing and end use needs, are produced. PHYSICALLY AND CHEMICALLY DEPOSITED THIN FILMS ON FORMING AND CUTTING TOOLS F.J. Teeter (Balzers Tool Cutting, USA). Thin films, applied by PVD, to improve wear resistance of tools and components were discussed with consideration of TiN and Ti(C,N). Test results for a CVD diamond coating on carbide cutting tools were presented.

Hardenability

of PM steels

HARDENABILITY MEASUREMENT ON PM STEELS

M.D. Acala et al (University of Udine, Udine, Italy). T. Prucher, C.S. Skena (Concurrent TechIt was reported that A120:3-25vol%Fe nologies Corporation, USA). nanocermets had been obtained by high Hardenability of PM steels was discussed energy reaction milling followed by ClP/ with respect to the effects of pores on heat HIP. Full density was attained at 1000°C. transfer and variations in composition. Hardness and toughness were reported to Progress in determination of hardenability be comparable with those of SiAlON data for PM steels was reported. Jominy test ceramic cutting tool materials. results for steels made from blended and prealloyed powders with 0.5 or 0.8%. Rockwell A hardness was used with shallow and deep hardening steel. PM’TEC’95 The following abstracts are Structure and properties were correlated of papers which were presented at the for quenched steels. International Conference on Powder Metallurgy which was held in Seattle, HARDENABILITY MICROSTRUCTURES USA, in May 1995. AND PROPERTIES OF SINTERED HARDENING ALLOYS

Titanium based materials PHASE FORMATION DURING REACTIVE SINTERING OF POWDERS G.L. Watt, S.B. Bhaduri (University of Idaho, Moscolw, Idaho, USA) A study of reactive sintering of Ti, B and ZrOz powders was described. Phase

42

MPR October

1995

A. DeRege et al (Domfer Metal Powders Ltd, Montreal, Canada). I Use of sinter hardening steels was outlined and it was noted that liquid quenching could be avoided. Sinter hardening ability of some alloys was investigated with regard to cooling rates, hardenability, hardness and microstructure. Materials selection data was given.

CHARACTERISTICS OF NITROCARBURISED NICKEL MOLYBDENUM ALLOYED PM STEELS M. Rosso et al (Polytechnic of Torino, Torino, Italy). The need for some parts to have hard wear resistant surfaces and tough shock resistant cores was discussed with reference to nitriding or carbonitriding. A scanning electron microscope study of the effect of carbonitriding on structure and properties, of a Ni-Mo-Cu-C steel was described. structures and properties were correlated.

Ceramic powders AUTO-IGNITION PROCESSING OF FINE ALUMINA-ZIRCONIA POWDERS S.B. Bhaduri et al (University of Idaho, Moscow, Idaho, USA). The production of nanocrystalline Alz03ZrOz from Al and Zr nitrates by furnace ignition with urea as fuel was described. Varying compositions were prepared and characterized for phase composition and microstructure by X-ray diffraction and scanning electron microscopy. The results were discussed.

Nitrogen based atmospheres EFFECT OF NITROGEN ATMOSPHERE COMPOSITION ON PROPERTIES OF CARBON STEEL COMPACTS D. Garg et al (Air Products and Chemicals Inc, Allentown, Philadelphia, USA). Importance of using the right N-based atmosphere for sintering steels to attain specified properties and to avoid decarburization, was emphasized. The paper described changes in properties arising from variations in atmosphere and optimization of gas composition. CARBON CONTROL SYSTEM FOR SINTERING ATMOSPHERES M.A. Phillips et al (Air Liquide America Corp, USA). C control in PM parts was discussed with respect to properties, machinability, dimensional tolerances, consistency and the effects of delubrication and sintering conditions. C control in sintering, by a continuous atmosphere control system, was described. Industrial results were reported to be good. EFFECT OF DEW POINT OF A NITROGEN-HYDROGEN ATMOSPHERE ON SINTERING AND PROPERTIES M.A. Phillips et al (Air Liquide America Corp, USA). It was reported that the sintering of FC0208 steel in dry N-lO%H gave a