Document RppDd1qGzjZ2YxJdMzX8qkG4z

. ^>--- -- -*->- r wn wi *- \ LEAD INDUSTRIES ASSOCIATION aax MADISON AVCNUI NEW YORK 17, N. V. Mar 2t I960 SUBJECT: SUMMARY OP RESEARCH REPORT To Meabers of the Lead Industries Association: You nay be Interested In the attached reprint, vhlch cumarlzes the results of a research project sponsored hr IXA In 1958 and terminated Is December of that year. Additional copies are available as long as our Halted supply lasts. Very truly yours. Att. Secretary 'U 0 uuil1 in Wi my-f*11 mum"** LI A 2A 2 89 A New Class of Lead'Base Alloys By D, S. WILLIAMS, /. A, HOUCK and B. I. JAFFEE* Experimental work iudk-atev (hat downing a metal powder in lead improves its tensile properties. Made by stirring powder* of low solubility such as copjxr. nickel and cobalt into molten lead, t!*e new alloys show promise in extending the usefulness of the heavy metal. (C5r, Q27a, R6g; Fb) 1 i :* Lf-so h as nvo <.iiAn.scrvjusTK s w hkh an* oht.iimd if a slight degree of solubility exists. 0 relatively umisu.il in a metal -- low molting tem perature (621 F.) and bnv solubility for most Fortunately, a nuinl>er of metals such as cobalt, copjser. iron, innhlKleiium. nickel and tungsten of the other metals. This lias led to tiie con slum the n-qimite low solubility in molten cept of forming two-plusc allow of lead and k*ad for satsfac!try alloying. All of these another metal by direct mixing of molten lead metals arc easily obt.iin.ihle in powdered form. atnl finely divuhd powderrxi nk-tal. Such alios . The composition of the lead phase4 could also ; might prose useful from tin* 'tundpoint of im* Ik * varied user a considerable range, with citlier provi-d properties of llic lead tase and miih < amoving elements completely soluble in Iwrth special characteristics of Hie second pliase liquid and solid lead or with alloying clononts additive. which form eutectics or precipitates in solid An exploratory study of lle feasibility of lead. However, tin: prr'vut invwtigatiott was forming alloys of this typo - redened to Ir t c - limits! to the uv of an utwlh*yod high-purity aftrT is lead-cemented allow--has !>ecii con- lead l>ase. ducted at Battelle Memorial Institute in cooper ation with llic' I^rad In<lti\tr>es Association. Mixing Procedures Results of this stmly are prrwuted here. TIk * imnt satisfactory mixing procedure it Seleiiion of Alloying Materials ch-tenniiKxl bv Oh * amount of solid material to Ik * added. For relatively small additions -- up f a*ad-cvnw*nted Um* are prepaml lv dirrxt to alxMit 15 vol.% - high-speed propeller mUm mixing of a finely divided solid phase in molten lead, rill* piiKvdurc will work satisfactorily are satisfactory. \M>en tlse amount of solid material is greater, tlse mixture becomes quite only if certain rcquirenviiiti are met. Foremost sluggish, with tlc characteristics of a wet among these are low soluhilitv and good wet ccnniit. These mixtures are best propared by tability. It is essential that the finely divided uv* of a slowly revolving crucible modeled solid material not dissolve in molten lead to after a cement mixer. A drawing of equipment anv appreciable extent. At the same time, to for preparing lead-cemented alloys having enhance mixing of tle solid and liquid phases, good wettability is required. Tliis is .nost easily \cwifcrrou Physical Metallurgy Div., Battrlie Memorial Institute, Columl*!*, Ohio. Reprinted from February 1060 Metal Progresa M 2031.01 u h w j i iii u'-Wffjniiimw ' " irtt~hhflM . ------- ` LIA2A290 .A i Hihr >iWirwV l#ctrk R*vttarx Fvr>oc# Steel Crucible (Itemovobl*) Fig i -- A/i/*mifu Vud to rrcfkirr t.raJ-Cctucutrd .\lfayi Containine \tvrt Than 15 Vnt.^* $i*hd Material Mobe leod fo*<jt*f9 SMl flec* Motor under hydrogen, these difficulties were overcome. (Note provision for main taining a hy drogen flame ov er the melt in Fig. 1.) These procedures in con junction with a high mixing tempera ture permitted the introduction of a number of metals into molten lead. The amount of powder added to the lead was varied from less than 15 to more than 50 vo|.*S; it was added di rectly to the melt, a small amount at a time, until mixing was complete. Characteristics of the Alloys Tlie divpervion of solid metal powder in molteu lead was cast directly from die mixing cmcible into an ingot mokl and solidified rapidly to prevent gravity' separation. Porosity was minimized In' vibrating the mold at low frequency more than 15 vol.^ additive is shown in Fig. 1. until the metal solidified. After being scalped Some of the metals - notably copper and to remove si.riace defects, tlie ingots were ex nickel -- stir quite easily into molten lead. truded to n>d at 500 to 550" F. Extrusion of the Others, however, resist mixing attempts because alloys generally proceeded satisfactorily. If of an oxide film on the powder surface. Ry mixing was incomplete, however, so that reducing tlie oxkle with hvdrogen, and mixing p^ket* of unwet |>owder were present in tlie ingot, severe surface cracks Table I - Tensile Properties of Several Lead-Cemented ABoyt often formed during extrusion. Metallograpliic examination CoMfOsmos I'rulloved lead Ni kel, 30 Nickel, IS <'.ripper, 30 Tungsten, 30 Iron, 30 n>uit, so 0>lh. 18 Sim.v . m IWIim. 51 SO 2480 4030 4450 1670 3110 4820 CtOSiCATlON RiiRcrmvoi Au l a Me""' 12 22 to IS <* q 26 j6 9 19 12 .V, of the extruded bars shows that tlie cemented alloys consist of a uniform dispersion of metal |xiwder in a lead matrix. No deformation of the metal pow der seems to occur during ex trusion. Figure 2 show's a typi cal structure. Very little of the me-id powder dissolve* during 0.503-in. bar samples iratrd at a rmtshead (jrrd of 0 (? in. prr min. mixing hut some agglonwratioii of particles is evident Table II * Corrosion of Lead-Cemented Altovs In H*SO at Utf'F, Ca j mo o s iiio n l*iulloyrd lead Copjier, 30vn| Cobalt. 18 fungitcn, 50 Wl h u it Lo is 9u Ha.* 40q. HfSO, ! ivf ii vi. n ew,. 0 IV 0 112 0 170 4.RA7 g. '*q in. 14.510 I 820 4.`.*u> *Sauij4e ii/r. 'i in. diameter by 2 in. lon^. As showm in Table I, metal powders gem-rally improve the tensile strength of lead. Excessive agglomeration apparently caused tlie low strength of the cemrnited alloy which contains iron. Although a complete study of the effect of powder size, shape and amount on tensile Jrength was beyond the scope of this Investi gation. some interesting trends are apparent In tlie data giv<*n in Table I. An optimum com position set-tm o exist for each powdif used. 0 ii'iniLia LIA2A291 o Fig. 2 -- Ty/uVti/ Structure of an Extruded ad-Ccttu nlcd .AHoy. Thu one contain9 30 col.% XL Although nickel particlet have agglomerated to unne extent, their dui}*e i* not changed by cilrtuion. 250 '< For example, .mi alloy <if IS col.0* Co is superior to (HK% containing JO vol.*^ ('o. but 30 \ol.rV Nl is Mijx'rior to 15 voF*** Ni. Also, proprities arc improxed most when a more spherical powder shape and a finer particle size arc list'd. Results obtained in this study suggest strongly that amount, size and shape of tlx* powder are ap preciably more significant in controlling tensile properties than composition of tlsc powder. Hie tensile properties of several cemented alloys as a function of temperature were also dctcrnJned. Representative data arc given in fig. 3. The ability of tlie lead-cemented alloy** to retain strength at elevated temperature b of considerable interest. If a similar benefit is obserxed in creep loading (no creep studies ha\T been made), alloys of this tvpe sliould raise the tipper temperature limit to whk-h lead alloys can be used. Measurements were also nude to determine the effect of tin* dispersed metal phase on tlse resistance of (lie alloys to c o t t o n ion in sulphuric acid at two concentrations, 40 and 95 vol.^. These data are shown in Table II. Corrosion resistance of tlx* lead-cemented alloys Is genirally inferior to that of unalloyed lead. How ever, the corrosion rate decreases more rapidly with time in tlx* cemented alloys than in unaltoyed lead, pos.ihly due to the dispersed powder which may cause tight adherence of the cor rosion jtrodiict, One allov with IS x-nl.% Co was superior to lead in vol.^ sulphuric acfd concentration. Extruded lead cemented alloys machine better than unalloyed lead. Tills suggests the possibility (bat these alloys may be amenable to joining with tlircadcd joints. Hie present study was intended to show the feasibility of producing a new class of lead alloys, the lead-cemented alloys. Hu* next step is to develop alloy** toward specific uses. For example, the data already available suggest that certain alloys may be especially useful in the chemical industry' as corrosion resistant alloys capable of bearing greater strc*sses at higher tem|)eratures tlun present alloys. The structures may also be of interest in bearing* metal applications. Alternately, applications may !>c hascJ upon some special characteristics of the disperses] phase -- the magnetic char acteristic of iron powder, for example -- with lead serxing principally as a hinder to permit easy casting and fabrication. Most materials, Ixrth metallic and nonmetallic, could probably Ik * made sufficiently wettable to permit tlveir introducti'xi into lead. Or perhaps special use's may be developed which are uniquely suited for these* alloys. A hypothetical example is a duplex radiation shielding material for use at elevated temperature, where l>oth components of the allov provide a specific shielding char acteristic. and (lie stmetme of the allox pros ides the necessary rc*sistafKe of flow. Fig 3 - Tcmde Strength of flercrof Lead. 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