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Some

Ternary and

Higher

Order

Platinum

Group

Metal Alloys

A PRELIMINARY REVIEW AND ASSESSMENT

OF THEIR CONSTITUTION AND PROPERTIES

By

I.

R.

McGill

Johnson Matthey Technology Centre

Platinum-based alloys find many applications in both high and low temperature industrial environments and are particularly suited to operation under corrosive aqueous and high temperature gaseous condi- tions. A wide variety of alloys exist which have been specifically designed for these purposes and in many cases they contain one or more non- platinum group metal. Although this situation is quite acceptable, there remains a fundamental need for systematic investigation of the basic pro- perties and constitution of platinum group metal alloys. Such a founda- tion in materials technology generally leads to an understanding of materials behaviour and provides guidance in designing new alloys with improved properties for existing and future applications. This review features the work which has been done on ternary and higher order platinum group metal alloys and provides access to important data.

In July 1857 a patent was granted to Jules Henry Debray for “Improvements in the Manufacture or Reduction of Platinum” (I), and the English rights of this important patent were immediately purchased by George Matthey. It was claimed within his specification that the method developed for processing platinum ores was of particular advantage, in that alloys of platinum and the different metals found within its ores were produced which possessed properties more advantageous than pure platinum. Indeed, in 1859, H. Sainte- Claire Deville and J. H. Debray declared that they had solved the problem of preparing a platinum-iridium-rhodium ternary alloy with excellent ductility for fabrication ( 2 ) . The weight percentages of rhodium and iridium specified by Deville and Debray were 5 and 19.6, respectively. The constitution of the platinum-rhodium-iridium system has not been well established and only recently has there been any attempt to characterise the structure and pro- perties of selected ternary alloys (3).

By the mid-19th century it had been recognised that the properties of platinum could be improved by selective alloying with other platinum group elements, so extending the already growing industrial applications of platinum.

The constitution and properties of binary alloys of the platinum group metals have been thoroughly investigated and equilibrium phase diagrams exist on all but a few systems. However, little has been done to characterise the 20 possible ternary systems. Published in- formation which is available on these systems is highlighted in Table I by a blue tint, while the type of data available on both these ternary and higher order systems is presented with references to the literature in Table 11. Clearly, the platinum-palladium-rhodium system has received the most detailed investigation primarily because of the major industrial im- portance of binary platinum-rhodium alloys, for example, in catalysis and as a constructional material for glass processing equipment. The

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UK ISSN 0032-1400

PLATINUM METALS REVIEW

A quarterly survey of research on the platinum metals and of developments in their applications in industry

V O L .

2 0

A P R I L

1 9 7 6

NO.

2

Contents

Sulphate Emissions from Automobile Exhaust

Palladium Alloys for Electrical Contacts

Coating Methods for Use with the Platinum Metals

Russian Research on the Platinum Group Metals

Hydrogen in Palladium

Carboxylato Complexes of the Platinum Group Metals

Abstracts

New Patents

38

44

48

53

54

54

64

69

Communications should be addrmsed to

The

Editor, Pkrtinum M& R&w

(3)

Platinum Metals Rev., 1987, 31, (2) 76 lensile strength at ambent or as {(TI %Elongatton Imp stress rupture tensile1 % Reductm in area 1creep:stress rupture tensik StIeSs rupture propertes

Hardnesslmicrohardns Modulus

of elastlcity RopomnaI limlt lrom tensile test Effect of impunties including gas solubility Creep characteristics Temperature coefficant of electncal resistancc

ReslStNlty Thermal

EMF

characteristics

Density Thermal

shock resistance Corroston propertes Ternary phase diagram andlor constitutm Mineralogy System Pt-Pd-Rh Pd-Rh-RU F+t-lr-Ru Pt-Pd-Ru Ir-Ru-0s Pt-Rh-RU

Pd-Rh-lr 3

Pt-Rh-Pd-RU Pt-Pd-lr Ir-Pt-0s 3

PI-Rh-lr 24

Pt-Rh-lr 2

Pt-Rh-Pd-Ru 133

Pt-Rh-lr-Ru 3

R-Rh-Pd-lr 15 5 6 7 8 9 10 1 1 12 13 14 15 16 17 Reference

4

3 4 5 18 19 20 19 2 21 22 23 19 20

--

-

-

-

-

-

-

-

-

T.M.bleI 1 i i

(4)

UK ISSN 0032-1400

PLATINUM METALS REVIEW

A quarterly survey of research on the platinum metals and of developments in their applications in industry

V O L .

2 0

A P R I L

1 9 7 6

NO.

2

Contents

Sulphate Emissions from Automobile Exhaust

Palladium Alloys for Electrical Contacts

Coating Methods for Use with the Platinum Metals

Russian Research on the Platinum Group Metals

Hydrogen in Palladium

Carboxylato Complexes of the Platinum Group Metals

Abstracts

New Patents

38

44

48

53

54

54

64

69

Communications should be addrmsed to

The

Editor, Pkrtinum M& R&w

(5)

UK ISSN 0032-1400

PLATINUM METALS REVIEW

A quarterly survey of research on the platinum metals and of developments in their applications in industry

V O L .

2 0

A P R I L

1 9 7 6

NO.

2

Contents

Sulphate Emissions from Automobile Exhaust

Palladium Alloys for Electrical Contacts

Coating Methods for Use with the Platinum Metals

Russian Research on the Platinum Group Metals

Hydrogen in Palladium

Carboxylato Complexes of the Platinum Group Metals

Abstracts

New Patents

38

44

48

53

54

54

64

69

Communications should be addrmsed to

The

Editor, Pkrtinum M& R&w

(6)

Fig. 3 100 hour etreee rupture and tensile characterietice of eelected alloye in the platinum(pa1ladium)-10 rhodium eyetem, aner Ref. 6. Tensile etrength data were obtained ue-

ing 1.5 mm diameter wire teet piecee annealed for 15 minutes at 1000°C in air prior to teet. The loading rate woe 10 mm/min

with a gauge length of 50 mm

4 0

a a

3 0 ;;

4

s

-

I

W

Lo W

v)

z 20

2

10 F

density of such alloys by the addition of palladium.

Excellent reviews of this subject have been published ( I I , 25). Although palladium can be

added safely to 5 weight per cent rhodium- platinum alloy without loss of high temperature strength, and with a slight improvement in duc- tility at temperatures up to 1250°C, further substitution for platinum causes a degradation of properties with respect to the parent binary

alloy. Figure 3 highlights the effect of palladium substitution for platinum in the pseudo-binary system platinum(palladium)-Io rhodium on both the tensile and 100 hour rup-

ture stress of alloys at temperatures of 1200 and

1400OC.

From mechanical property data reported by Rytvin, Kuz'min and Petrova (8) on a selection of platinum-rhodium-palladium alloys tested at temperatures of I 100 to 1400OC, Figure 4, it is

Fig. 4 The high temperature tenaile strength of rhodium wae interpolated from

data presented in Ref. 30. The data for platinum, pdadium and the two ternary dloye were taken from Ref. 8. Wire ramplee 1.3 mm in diameter were annealed for 3 h o w at 130OOC and then teeted with a loading rate of 6 mmlmin

(7)

I

Fig. 5 Elongation data have been taken from Ref. 8 and were obtained over a

50 mm gauge length. Pre-tert conditionr and loading rate w e r e ar dercribed in Figure 4

Fig. 6 Elongation valuer for d o y r containing 20 weight per cent rhodium and for the d o y with 50 weight per cent platinum were obtained using a 50 mm gauge length. Elongation valuer for the remaining aUoyr were obtained over a 30 mm

ewelength(10)

recommended that palladium-rhodium and platinum-palladium-rhodium alloys be used for high temperature applications. The tensile pro- perties of 20, 10, 15 and 7 weight per cent rhodium-platinum binary alloys, however, still exceed those of any other alloy investigated. Rytvin and colleagues report tensile strength values for the platinum70 palladium-Io rhodium alloy at 1200 and 1400OC to be 22.56 and 5.88MPa7 respectively. Reinacher, however, reports respective values of 28.24 and

I2.75Mh (10). These differences reflect the

variation in pre-test annealing conditions and test sample geometries. Per cent tensile elonga- tions at fracture for a number of ternary alloys have been reported (8, IO), and are shown in Figures 5 and 6. Again there is a striking dif- ference in the values of elongation at fracture for the platinum-70 palladium-

10 rhodium alloy. It is reported that the

platinum-70 palladium-Io rhodium alloy fails in an intercrystalline manner at 140o0C, but with

(8)

Fig. 7 Data have been taken from Ref. 10, with pre-teat rample conditioning and teneile test eonditionr ae described in F b3

an elongation at fracture equivalent to that of pure platinum (10).

Perhaps the most important observation made on the high temperature tensile proper- ties of the platinum-palladium-rhodium alloys with palladium contents between 40 and 70

weight per cent, and rhodium contents between

10 and 20 weight per cent, is the low ductilities shown by these alloys between goo and I IOOOC.

Values of the per cent reduction in area after tensile test give some indication of this effect and are- shown in

Figure

7, after (10). An ex- planation of this behaviour and an interpreta- tion of the data has been given (I I).

Creep and Streee Rupture Properties

The stress rupture characteristics of alloys in the platinum-palladium-rhodium system, with

Fig. 8 100 hour etresr rupture data have been compiled from Ref. 7 and Ref. 10. The materials teeted at 900,1250 and 150OOC (7) were pre-conditioned for 60 min at 9OO0C, 30 min at 120OOC and 10 min at 150OOC in air, rerpectively. The other three were pre-conditioned for 15 min at 140OOC in air (10)

(9)

rhodium contents up to 20 weight per cent have

been thoroughly investigated (7, 10, 16) and previously reviewed (I I, 25). There is no doubt that the high temperature performance of platinum-rhodium binary alloys containing up to 20 weight per cent rhodium exceeds that of any ternary alloy examined to date. Ternary alloys which have been investigated fall into two catagories; (i) alloys with a combined rhodium and palladium content not exceeding 20 weight per cent, and, (ii) alloys containing between 40 and 70 weight per cent palladium.

A comparison between the 100 hour stress to rupture properties of example materials from each of these categories can be seen in Figure 8,

(7, 10). Figures 9 and 10 present 100 hour stress rupture data on selected binary alloys, and pure elements for reference.

At temperatures up to 125ooC, the properties of low-palladium ternary alloys, Figure 8, com- pare favourably with binary platinum alloys containing up to 5 weight per cent rhodium, Figure 9. A slight improvement in ductility has also been observed.

Fig. 9

Re&. 30, 32 and 33

100 hour etreee rupture data presented here have been compiled from

Fig. 10

piled from Refe. 30 and 33

100 hour etrese rupture data for these five binary elloye have been com-

(10)

Fig. 11 Theae 100 hour rupture f-8 have 'been compiled from Ref. 7

Fig. 1 2 Theae figurer of the 1 0 0 hour atreaa-rupture propertiea of platinum-5 rhodium-palladium d o y r have been compiled from Ref. 7

Fq. 1 3 Data for the atreaa-rupture propertiea of platinum-3 palladium-7 rhodium have been compiled from Ref. 7

(11)

Fig. 1 4

alloys have been compiled from Refs. 1 0 and 1 6

Stress-rupture properties, at 1200°C, of four high palladium ternary

Fig. 15

ties being determined at 140OOC

These data have been compiled from Ref. 10, the stress-rupture proper-

At temperatures between 1250 and 150o0C, alloys containing less than 5 weight per cent palladium and with rhodium contents below 10

weight per cent show an increase in strain com- pared to the binary alloys platinum-5 rhodium and platinum-Io rhodium, Figure 1 1 . An in-

crease in the palladium content to 10 weight per cent, however, decreases rupture strain and marginally reduces rupture strength (7). The effect of palladium on the IOO hour rupture stress of a platinum-5 rhodium alloy at

temperatures between 900 and I 5m°C is shown in Figure 12.

The results of investigations on ternary

replacements for the most commonly used platinum-rhodium binary alloy, that is platinum-Io rhodium, have lead to the develop- ment of a compromise alloy, namely platinum-3 palladium-7 rhodium. The stress rupture properties of this particular alloy are presented in Figure 13 and, by reference to platinum-palladium-rhodium alloy

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Figure 9, it is only at operational temperatures of I 500OC that the material shows inferior pro- perties to that of platinum-ro rhodium. An un- fortunate consequence of using palladium as an alloying additive to binary platinum-rhodium alloys is the tendency of most materials to fail by intercrystalline cracking at intermediate temperatures between 850 and 10ooOC. The lack of ductility in this temperature regime restricts their use to low stress applications.

As

far as the high palladium alloys are con- cerned, results on the stress rupture characteristics of selected materials obtained by Reinacher would suggest that the platinum-40 palladium- 10 rhodium alloy has adequate strength properties for industrial ap- plications where the operating temperature does not exceed 120o0C (10, 16). Figures 14 and I 5 compare the stress rupture properties of high palladium ternary alloys at 1200 and

I 50o0C, respectively.

An attempt to correlate the high temperature creep properties of a selection of platinum- palladium-rhodium alloys with palladium and rhodium concentration has been reported (9). Reasonable agreement between experimentally determined values for rupture life and creep

rate against calculated values was found. The experimental creep rate data from this work have been reproduced in Figure 16.

The effects of alloying platinum with palladium, rhodium, iridium and ruthenium on the formation of dislocation structures in binary alloys has been investigated by Usikov, Stepanova and Rytvin (17)~ and highlights the resulting effect on creep rate, Figure I 7. Clear- ly, palladium additions to platinum up to 10

weight per cent have virtually no effect on the stacking fault energy of platinum, with the result that there is little difference between the creep properties of these materials. The effec- tiveness of other platinum group metals in reducing the stacking fault energy of the platinum solvent and thereby improving high temperature creep properties was found to be

ruthenium>iridium>rhodium>palladium.

This

behaviour is undoubtedly reflected in ter- nary and higher order alloys and clearly offers the opportunity for developing new alternative heat resistant alloys.

Electrical Resistance and Thermal

EMF

The electrical resistance and temperature coefficient of resistance of a complete range of

Fig. 1 6 Creep rater were determined on wire rampler of 0.8 mm diameter, with

a gauge length of 50 mm and an npplied rtrerr of 4.83 MPa. Prior annenling war carried out at 1350 and 1425OC for 3 hourr. Experimentd valuer reported were used to ertablirh time-to-failure and creep rate equationr nr functionr of palladium nnd rhodium d o y content (9)

(13)

alloys in the platinum-palladium-rhodium system have been measured and reported (6). Iso-resistance plots at 25OC are provided together with a similar graphic presentation for the temperature coefficient of resistance. The hghest electrical resistance and lowest temperature coefficient of resistance is shown by an alloy platinum-so palladium-30 rhodium. Thermal e.m.f. values for alloys containing up to 10 weight per cent rhodium against platinum were determined for the 100 to 10ooOC

Alloy (wt. %I

G

temperature range, and are presented in the form of pseudo-binary sections and a constant thermal e.m.f. contour map. Thermal e.m.f. results are consistent with the view that the platinum-palladium-rhodium ternary system shows complete solid solubility.

95

-

'

85 10

80 15 75 20 70 25 60 35 50 45 4 0 55 30 65 20 75 10 85 5 90

-

95

~ 90 5

Environmental Propertiee

The effect of thermal cycling on the creep ductility of platinum-rhodium, platinum- palladium-rhodium and platinum&ladium-

~~~ ~ ~ ~ ~~~~~~~~~~ ~~~~ ~

la#. I V

Room Temperature Tensile Data for Platinum-Palladium-Rhodium Alloys

I

with Rhodium Contenti of 5. 10 and 20 weight Der cent

5 5 5 5 5 5 5 5 5 5 5 5 5 5 90 80 70 60 50 40 30 20 10 -

-

10 10 10 20 10 30 10 40 10 50 10 60 10 70 10 80 10 90 10

80

-

20

70 10 20

60 20 20

50 30 20

40 40 20

30 50 20

20 60 20

- 80 20

Tensile strength

o (MPe)

225.5 264.8 274.8 304.8 362.8 324.9 332.4 329.8 309.8 309.8 284.9 257.3 243.6 284 323.6 374.6 412.5 406 406 360 357 330.5 281.1 372.6 416.8 443.9 462.2 512.2 568.4 562.1 487.2 500.2

" .

Young's modulus

E x lo-' (MPa)

194.2 186.3 180.5 176.5 170.6 168.7 162.8 158.9 156.9 149.1 147.1 145.1 141.2 133.4 211.8 200 186.3 174.6 166.7 160.8 157.8 153 151 149 237.4 225.5 21 5.7 206 196 190.3 184.4 172.6 Normalised tensile strength

olE x 10'

1.16 1.42 1.52 1.72 2.13 1.93 2.04 2.07 1.97 2.07 1.94 1.77 1.73 2.13 1.53 1.87 2.2 2.33 2.43 2.23 2.26 2.16 1.86 2.5 1.76 1.97 2.14 2.49 2.9 2.95 2.64 2.9

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Fig. 17 Test samples in sheet form were annealed for 2 hours at 90 per cent of the melting point, cold-rolled to 0.5 mm sheet (6 per cent reduction) and cut to 3 mm discs for experimental work to determine the potency of the second ele- ment on the creep properties (1 7)

rhodium-ruthenium alloys has been studied by of cycles required to achieve a crack length of Medovoi and Rytvin (13). Sheet samples of I mm was used as an indication of thermal

alloy were held between ceramic plates and shock resistance. Ductility was determined heated by electrical resistance. The thermal cy- from the creep time at 140o0C with an initial cle was between 1400 and I ~ ~ O O C , with a full stress of 4.9 MPa. The results of this investiga- cycle lasting 30 seconds. Time spent at the tion are presented in Figure 18. The binary lowest temperature was 5 seconds. The number platinum-rhodium alloys and also the

Fig. 18 To determine resistance to thermal shock, samples were cycled between 1350 and 14OOOC. Tests were carried out on vacuum melted materials, forged at 1100 to 150OOC and rolled to 0.5 mm thickness (40 per cent reduction). Sam- ple dimensions were 6 0 ~ 1 0 ~ 0 . 5 mm with a central hole serving as a stress con- centrator. AU the samples were annealed at 145OOC for 2 hours prior to test (13)

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Fig. 1 9 Irothermal rectionr at 140OOC are given for variour platinum group metal ternary ryrtemr, &er Refr. 3 and 19

I

platinum-15 palladium-5 rhodium alloy had the was that alloying elements which cause a reduc- highest thermal shock resistance of all the alloys tion in grain size and creep ductility of tested. The basic conclusion from this work platinum alloys also lower the resistance to

(16)

thermal shock in the range 1350 to 1400OC. In 1975, Stepanov, Chernyshova and Shevelev reported on the behaviour of a platinum- I 5 palladium-5 rhodium alloy and two binary palladium-rhodium alloys during standard welding operations (14). It is clear from this investigation that an alloy containing palladium is more prone to weld crack forma- tion than platinum-rhodium binary alloys. The effects of micro-impurities on weld crack for- mation were also investigated. The presence of silicon, calcium and aluminium was found to exacerbate the cracking phenomenon in all alloys investigated.

Not only does the presence of metallic im- purities affect the properties of platinum group metal alloys but gaseous impurities can significantly alter in-service behaviour. Kalinyuk and Solomentsev have investigated techniques for the determination of gaseous im- purities in noble metal alloys ( I 5 ) . Oxygen and

hydrogen determinations are presented for platinum and platinum-rhodium, platinum- palladium-rhodium and platinum-palladium- rhodium-iridium alloys. However, no alloy compositions are given as comparative analysis techniques were being evaluated.

Other Ternary and Higher

Order Systems

The mechanical properties of two palladium alloys containing rhodium and ruthenium, palladium-I rhodium-4 ruthenium and also palladium-3 rhodium-2 ruthenium, have been reported by Wise and Eash (4, 5). Ruthenium is shown to be extremely effective in hardening palladium and increases the annealing temperature from 80o/90o0C to 1ooo/110o~C. The tensile strength of palladium-I rhodium- 4 ruthenium in the fully annealed state is ap- proximately 90 per cent greater than that of palladium. An increase of 42 per cent is shown for the palladium-3 rhodium-2 ruthenium alloy. Both alloys exhibit reductions in cross-sectional area of greater than 84 per cent in either the an- nealed or as-received condition. These authors also report a precipitation hardening effect at annealing temperatures of 800°C for the high

ruthenium alloy which is similar to that observ- ed in the binary platinum-20 iridium alloy. The internal oxidation of ruthenium may be the cause of such behaviour, resulting in an oxide dispersion strengthened material.

The 1400OC isothermal cross-section of the palladium-rhodium-ruthenium phase diagram has been reported by Raevskaya, Vasekin and Sokolova (3), indicating the existence of a two phase region based upon the binary solid solu- tion of platinum-rhodium and the ternary ter- minal solid solution of ruthenium. Isothermal cross-sections at 140ooC for the ternary systems iridium-rhodium-ruthenium, platinum- palladium-iridium and palladium-rhodium- iridium are also presented. From microstruc- tural and X-ray analyses it was shown that a complete series of ternary solid solutions were present in the platinum-rhodium-iridium and platinum-rhodium-palladium systems at 1400°C, and that the miscibility gaps in the

palladium-iridium-platinum(rh0dium) systems were due to decomposition of the solid solution in the palladium-iridium system at 148oOC (27).

Hardness variations are also presented as a function of alloy composition in the palladium- iridium-rhodium and rhodium-ruthenium- palladium systems, and are used to confim the position of phase boundaries. Some indication of the constitution of the platinum-ruthenium-

rhodium-palladium(iridium) quaternary systems has been provided based upon electron probe microanalysis, hardness and lattice cell volume changes of selected experimental alloys. Similar constitutional work on the ruthenium-

platinum-rhodium(palladium)(iridium) ternary systems has been reported by Raevskaya, Vasekin, Konobas and Chemleva (19).

A

schematic presentation of the ternary phase diagrams at 140oOC is shown in Figure 19, after (3) and (19).

In attempting to define optimum composi- tions in complex alloyed platinum alloys for use in heat resistant applications, Norvik, Rytvin, Medovoi and Ulybysheva examined statistically a range of alloys in the platinum-palladium- rhodium-gold-iridium system (34). The results

(17)

of creep rupture tests carried out at 1400OC would initially indicate that a platinum alloy of nominal composition, platinum-Io palladium-Io rhodium, with 0.1 weight per

cent of gold and iridium was a suitable can- didate for further development. This particular alloy tested at 1400OC under an applied load of 4.9MPa, demonstrated a rupture life capability of 77 hours which is indeed comparable with the properties of platinum-40 palladium-20 rhodium, Figure I 5, and platinum-10 rhodium.

It was also clearly demonstrated that time-to- failure increased with a decrease in the palladium content and an increase in the rhodium and gold contents. The need for an iridium content of 0.1 per cent was stressed. Further work identified an alloy, platinum-6o palladium-Io rhodium containing 0. I per cent gold, and excluding iridium, which had a rup- ture life of 60 hours. If this is indeed the case,

then the effect of gold on the stress rupture pro- perties of platinum-palladium-rhodium alloys is quite remarkable, Figure I 5, as the rupture life quoted by Reinacher for the platinum-6o palladium-Io rhodium alloy was 1.25h (10).

Conclusions

Considering the importance of the platinum group metals in many high temperature in- dustrial applications, it is surprising that there has been only limited systematic study of the constitutional characteristics and properties of ternary and higher order systems. What is available in the literature has provided impor- tant guidelines for those involved in the engineering development of platinum group metal products. Clearly there is a need for fur- ther studies of these systems which may result in the development of additional alloys suitable for use in aggressive environments.

References

I British Patent 1947; 1857

2 H. Sainte-Claire Deville and J. H. Debray, Ann. Chim. Phys., 1859, 56, 385

3 M. V. Raevskaya, V. V. Vasekin and I. G. Sokolova, J . Less-Common Met., 1984, 99, 137 4 E. M. Wiseand J. T. Eash, T r a m A I M E , 1935,

179 313

5 E. M. Wise and J. T. Eash, Trans.AIME, 1938, 128, 282

6 W. A. Nemilov, A. A. Rudnitski and R. C. Polya- kova, lev. Sekt. Platiny, 1951, 26, 16 7 G. Reinacher, Metall, 1962, 16, (7), 662 8 E. I. Rytvin, V. M. Kuz’min and A. E. Petrova,

Metalloved. Term. Obrab. Met., 1967, (4), 58 9 I. E. Rytvin, V. M. Kuz’min and Yu. V. Meitin,

Metalloved. Term. Obrab. Met., 1969, (2), 71 10 G. Reinacher, Metall, 1971, 25, (7), 740

1 1 A. S. Darling, Platinum Metals Rev., 1973, 17,

12 French Patent 2,135,445; 1971

13 L. A. Medovoi and E. I. Rytvin, Metalloved. Term. Obrab. Met., 1974, (8), 76

14 V. V. Stepanov, T. A. Chernyshova and V. V. Shevelev, Fiz. Met. Metalhed., 1975, 39, (I), 183

1 5 N. N. Kalinyuk and A. N. Solomentsev, Zavod.

Lab., 1976, 42, (31, 271

16 G. Reinacher, Metall, 1973, 27, (7), 659 17 M. P. Usikov, G. S. Stepanova and E. I. Rytvin,

18 J. G. Want, Platinum MetalsRev., 1961,5, (2), 42 (41, 130

Russ. Metall., 1981, (5), 114

19 M. V. Raevskaya, V. V. Vasekin, U. I. Konobas and T. A. Chemleva, Vesm. Mosk. Univ., Ser. Khim., 1984, 25, (I)

20 V. V. Vasekin, M. V. Raevskaya and E. I.

Rytvin, “Summary of Reports to the 4th AU

Union Meet. on Constitution Diagrams of Metallic Systems”, ed. N. V. Ageev, Nauka, Moscow, 1982, p. 77

21 R. S. Polyakova, Thesis, “Phase Diagram of

Systems Pd-Ru and Pt-Pd-Ru”, Inst. Met., Akad. Nauk SSSR, 1956

22 L. J. Cubri, Miner. Sci. Eng., 1972, 4, (3), 3

23 S. A. Toma, Thesis, “Mineralogical Studies on Some Synthetic Alloys and Minerals of the Platinoid Group”, Aston University, U.K., 1975 24 S. A. Toma and S. Murphy, Can. Mineral., 1977,

15, 59

25 A. S. Darling, Platinum Metals Rev., I 962,6,(4), 148 26 A.S.Darling,Platinum Metak Rev., 1961,5,(2),58 27 E. Raub, J. Less-Common Met., 1959, I, 3 28 E. Raub, H. Beeskow and D. Menzel, Z.

29 A. A. Rudnitskii, R. S. Polyakova and I. I.

30 “Edelmetall-Taschenbuch”, Degussa, Frankfurt

31 W. Koster, Z . Metallkd., 1948, 39, (I), I

32 G. Reinacher, Z . Metallkd., 1962, 53, (7), 444 33 G. Reinacher, Metall, 1961, 15, (7), 657 34 F. S. Novik, E. I. Rytvin, L. A. Medovoi and L.

P. Ulybysheva, Sou. N o n - F e r n Met. Res., Metallkd., 1959, 50, (71, 428

Tyurin, I m . Sekt. Platiny, 1955, 29, 19

a M., 1967

1980, 8, (31, 298

Figure

Fig. 3 100 hour etreee rupture and tensile characterietice of
Fig. 5 Elongation data have been taken from Ref. 8 and were obtained over a 50 mm gauge length
Fig. 7 teneile test eonditionr ae described Data have been taken from Ref. 10, with pre-teat rample conditioning and in Fb3
Fig. 9 Re&. 30,
+6

References

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