Literature Review~~~~~~~~~~~

FERROUS MATERIALS

SINTERING OF IRONWITH CARBON, COPPERAND NICKEL ADDITIVES

vS Styskin (The Wakefield Corporation)

Relationships between the hardness, dimensionalbehaviour, density change and chemicalcomposition of sintered materialsarc studied. Thechemical composition of the studied materialsgenerally fallwithin the limits ofMPIFstandard 35materials FC-0200-FC-I000 and FN-0200-FN-040B.Established a strong correlation between thedimensional growth and density decrease ofiron-carbon-copper alloys. Addition of nickel tothese alloys increases the hardness, decreases thegrowth and density change during sintering.Increase of nickel amount results in the smallerdimensional growth.

PERFORMANCE CHARACTERISTICS OF A NEWLOW-ALLOY PM MATERIAL

JJFulmer, R JCauston [Hoeganacs Corporation)

The physical, chemical, and green properties of anew low-alloy PM material will be presented. Inaddition, tensile and impact properties will besummarized for a range of densities and carboncontents and the results will be compared with theperformance of existing low-alloy materials.Tensile and rotatingbending fatigue propertieswillbe presented for selected, heat treated samples.

PHOS-COPPER AS A STRENGTH ENHANCERFOR IRONPARTS

F W Hinger (Zinc Corp. of America)

This paper investigates the mechanical propertiesof sintered iron parts made with iron powder withphos-coppor powder additions. Parts made withphos-copper powder additions show animprovement in transverse rupture strength androckwell hardness over parts made with copperadditions. An experiment was designed to evaluatethe effects of phos-coppor addition on themechanical properties of iron parts.Variousblendsof iron powder, phos - copper powder, and graphilewere made. Transverse rupture bars were pressedfrom each blend to a 6.9 glccdensity. The test barswere sintered in a belt furnace at 2050F. Thesintered bars were evaluated for sintered density,change in length from die size, transverse rupturestrength. and rockwell hardness. A number of thetest bars were examined metallographically. Theseexperiments determined the optimum percentagesof phos-copper and graphite to obtain the greatesttransverse rupture strength. II also compares theproperties of transverse rupture bars made withphos-copper powder additions versus ones madewith copper powder additions.

AN INVESTIGATION INTOTHEMICROSTRUCTURE AND MECHANICALPROPERTIES OF AN ADVANCED T15 HIGHSPEED STEEL

B Hribernik, G Hackl (DI Universityof Mining andMaterial Science)

576

Samples of T15 HSS were made by the Ospreyprocess and also from gas atomised and HlPedpowder. The samples were forged to the samedimensions. Carbide size and distributions weremeasuredby automatic image analysisofboth typesof material in the unetched state. The mechanicalproperties arc being investigated.

ENGIr-.'EERING PROPERTIES OF410 STAINLESSSTEEL

H D Ambs,M Svilar (SCM Metal Products Inc)

This paper describes the manufacturingproceduresused toachievemechanicaland physical propertiesfor engineering use. II will describe the practicalconsideration of carbon and alloy additions,sinteringatmosphere effectsand post sinteringheattreatments. Microstructural illustrations will helpexplain the results.

THEPROCESSING AND PROPERTIES OF 400SERIES PM STAINLESS STEELS

JH Reinshagen, J C Witsberger [Ametek, Inc)

In this paper the 400SeriesPMalloys are reviewed.First, the compositions, characteristicsand powderproperties are discussed. Following this,compaction and proper sintering techniques arereviewed, and the properties that can be expectedin finished parts arc detailed.

NITROGEN ALLOYED STAINLESS STEELSPRODUCED BYNlTRIDING OF POWDER

A Johansson. et al, (Swedish Institute for MetalsResearch)

Stainlesssteels havebeen gasatomized, nitrided innitrogen gas and consolidated by HIP or hotextrusion. Steels with up to 0.6 wt% nitrogen havebeen produced. NitridationofTi alloyed austeniticsteels has been shown to produce fine dispersionsof TiN. Nitrogen in solid solution and fine TiNdispersions strengthen the steels significantly. Anexample is a type 316 stainless steel consolidatedto full density by hot extrusion at 1150C. For a Ti­and N-content of 0.70 and 0.24 wt%. respectively,the yield strength was raised by a factor of about 3within the temperature range up to 600C ascomparedto the standard 316steel. Creep strengthat 700C was also significantlyenhanced. Nitrogenalloyingof stainless steel powder can.also improvethe pitting corrosion resistanceof the consolidatedprodnct.

COPPER

LUBRICANT CHANGES FORCOPPER·TINMIXES

A B Backensto (Consultant)

Laboratory experimentswereperformedtoevaluatehow different lubricantsaffectedpowder propertiessuch as apparent density. flowcompressibility, andgreenstrength. Studies werealso madeof theaffects

on dimensional change and sintered strength atdifferent sintering temperatures. Graphshavebeenprepared to show the relationships.

PROPERTIES OF OXIDE DISPERSIONSTRENGTHENEDIPRECIPITATION HARDENEDCOPPER POWDERS

N \V Blossom. D B Brimhall (American ChemetCorp.)

Oxide dispersion strengthening and precipitationhardening were used together to enhance themechanical properties of copper matrix materialsfor high-temperature, high-conductivityapplications. The powders evaluated wereCu-AlzOJ• Cu-Zr, Cu-Zr- AlzOJ,and C\I-Zr-Cr-AhOJ'The powders were cold pressed and sintered orwere extruded and drawn. Mechanical andelectrical properties of these new materials arereported.

EFFECTS OF SINTERING PROMOTERS INPMCu-Zn-AI SHAPE MEMORY ALLOYS

SOC Lin. et at (Industrial Technology ResearchInstitute)

Cu-AI, Cu-Znmaster-alloyed powders and pure Cu.powder were used. Different amount of AlFJ,NaJAIF6• HBOJwereadded individually assinteringpromoters.Thosesinteringpromotersare supposedto eliminate the existingAlzOJ film which inhibitsthe diffusing process. Powders and sinteringpromoters were mixed by a V-type mixer andpressed at a compacting pressure of 700~{Pa.

Compactswerethensintered in Hzatmospherewithsintering temperaturesrangingfrom700C to 1000C.Measurements of grain size and relative densitywere conducted to evaluate the effects of sinteringpromoters. DSC was also used to verify the shapememory effect.

INTERMETALLICS

REACTIVE SINTERING AND REACTIVE HOTISOSTATIC COMPACTION OF HIGHTEMPERATURE INTERMETALUC COMPOUNDS

R M German (Rensselaer Polytechnic Institute)

This paper describes the effects of variousprocessinn factors on fabrication of densealuminid;s with primary emphasis on NiJAI.Resultson the fabrication ofseveralotheraluminidecompounds will be discussed, including NiAI,TiA\,TaAlJ and NbAlJ. Densities in excess of 97%of theoretical are possible through appropriateselection of particle sizes, composition, greendensity, heating rate, atmosphere, maximumtemperature, and hold time. The sintered densitydepends on the amount of liquid formedat the fir~t

eutectic temperature and the connectivity of thisliquid. Because the liquid persists for only a shorttime, it is important that the several processparameters be carefullycontrolled to optimize thesintered density. Subsequent processing (he?ttreatment and containerless hot isostaticcompaction) can then be used to remove theresidual porosity and homogenizethe compact.

MPR JulylAugust 1990