Solubility of scandium in manganese and iron at elevated temperatures

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101

Single crystals appear to be prone to twinning, although the ability to twin appears to be dependent on the number of electron beam melting passes, or consequently residualimpurities. A single crystal specimen having two passes twinned and fractured readily with one hammer blow at -rg6”C. However, a crystal which had five passes did not fracture or twin when subjected to a similar test. On a subsequent blow with the hammer, this single crystal did, however, also fracture and twin. Twins in single crystal tungsten have characteristics of twins observed in one or another of the body-centered cubic metals. In single crystal tungsten, low working temperatures, and/or deformation twins inhibit recrystallization. The twinning action also appears to initiate microcracks. Although single crystals are prone to twin, the ability to twin appears to be dependent on the number of passes of the electron beam and consequently certain residual impurities. Twins in tungsten also appear to form at a much higher temperature than previously reported. R. H. G. H.

Metals Research,

WestinghozLseElectric Corp.,

SCHNITZEL KEITH

Lamp Division, Bloomfield,

N. J. (U.S.A.)

1 H. W. SCHADLER, Trans. AZME, 218 (1960) 649. 2 R. H. ATKINSON elal., W.A.D.D. Tech. Report. 60-37, (1960). 3 C. S. BARRETT, Structure of Metals, McGraw-Hill Book Co., New York, 1952. 4 C. ~.BARRETTAND R.BAKISH, Trans. AZME,212 (1958) 122. 5 F. MUELLER AND E. PARKER, O.N.R. Report, N. V. zzz-p-27, (1960). 6 E. T. WESSELS, L. L. FRANCE AND R. T. BEGLEY, Westinghouse Research Report, (1960). 7 J.T. FOURIE,F.WEINBERGAND

F. W. BOSWELL,

AdaMet.,

II-0103~I-PI,

(Ig6o)85.

Received August r6th, 1961 J. Less-Common

Metals,

4 (1962)

98-101

Solubility of scandium in manganese and iron at elevated temperatures

INTRODUCTION

A limited quantity of metallic scandium being available, it has been possible to prepare a few dilute alloys of this metal in both manganese and iron. Alloys have been examined by thermal analysis in thoria refractories under an atmosphere of argon, as described elsewherei, and by microscopical and X-ray methods. The solvent metals were of the same purity as those employed in previous work of a similar nature2. Only a little over I g of the scandium was available so that the results are confined to alloys containing less than 1.5 at.% of the solute. The results are only fragmentary, but enable the forms of the phase diagrams to be deduced, and show the influence of scandium on the allotropic modifications in manganese and iron. J.

Less-Common

Metals,

4 (1962)

101-103

102

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In each case, the most concentrated alloy was prepared first, and dilute alloys by adding more solvent metal and remelting. MANGANESE-SCANDIUM

The suggested form of the phase diagram is shown in Fig. ra. The limit of solid solubility is about I at.% in the /I and 6 phases, but less than 0.4 at.% in the y

(4 I T

Y ii. L

\

EOO-1

1

\

1 B+L

\

I 5 Mn-Sc

I 5

At.%

At.% Fe -SC

Fig.

I.

phase. An alloy containing 0.25 at.% scandium indicated that the liquidus and solidus were initially raised by addition of solute, while the y/S transition temperature was also raised and the /l/y temperature depressed. These arrests seem unlikely in view of those obtained at higher solute concentrations and may have arisen due to a scavenging effect by the scandium. Microscopical examination of the 0.25 at.% and 0.5 at.% alloys showed them to be one phase, while the 1.5 at.% alloy was two phase. There was no microscopical evidence for a eutectic and all alloys gave reflections corresponding to the /?-manganese structure. It seems that the y-field is closed by a eutectoid at about 1125’C and the B-field by a peritectic at 1140°C, as shown in Fig. ra. The LX/Btransition temperature must be markedly depressed by addition of scandium. IRON-SCANDIUM

Two alloys of iron were examined containing 0.25 at.% and 0.6 at.% of scandium respectively. The results can be only tentative but suggest that the phase diagram is of the form shown in Fig. rb. The 0.25 at.% alloy indicated a depression of the y/S transition temperature and when examined microscopically was almost one J. Less-Common

Metals, 4 (1962) 101-103

103

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phase except for traces of precipitate at the grain boundaries. The 0.6 at.% alloy was two phase, the second phase being the first compound (possibly Fe&c) occurring as a eutectoid. The C+J transition temperature showed considerable hysteresis, but compared with pure iron showed that the transition temperature was raised by addition of scandium. ACKNOWLEDGEMENTS Thanks are due to Professor W. HUME-ROTHERY for laboratory facilities, and to Mr. K. SPEIGHT of the B.I.S.R.A. for chemical

accommodation and analyses of alloys.

Department of Metallurgy, Oxford University (Great Britain)

A. HELLAWELL

1 A. HELLAWELLAND W. HUME-ROTHERY, Phil. Trans. Roy. Sot. (London), 2 A. HELLAWELL, J. Less-Common Metals, I (1959) 343. Received

August

Ser. A. 249 (1957) 417.

zest, 1961 J. Less-Common Metals, 4 (1962) 101-103

Angles between some low index planes in rhenium

lattice

Recent interest in the metal rhenium requires a better understanding of its basic properties. A knowledge of the geometry in the lattice will be of value in solving problems regarding the slip mechanism and the effect of crystallographic orientation. The angles between some low index planes are presented in Table I (see pp. 104-106), calculated from the equation below:

where Q, is the angle between two crystallographic planes @I, kl, in, II) and (122,kz, iz, 12) using the Miller-Bravais indices; the values of a and c are taken as 2.761 il and was performed in an I.B.M. 650 computer 4.458 A, respectively 1. The calculation with an accuracy * I minute. Raytheon Co., Newton, Mass. 1 H. E. SWANSON

Received

AND

April Izth,

C. FENG

(U.S.A.)

R. K. FUYAT, Natl. Bur. Standards (U.S.) Circ. No. 53y, Vol. 2 (1953) 13. 1961 J. Less-Common

Metals, 4 (1962) 103-106