US 3161503 A
Description (OCR text may contain errors)
United States Patent ice Patented Dec. 15,- 1964 Therefore such alloys while being extremely useful at 3,161,503 normal or. so-called room temperature are restricted in COOSION RESISTANT ALLO Gilbert A. Lenning, Las Vegas, and Barry W. Rosenberg,
Henderson, New, assignors to Titanium Metals Corpodesirable embrittlement during such a long exposure time.
practical applications, and do not appear to be suitably employed exposed to relatively high temperatu'res'for ration of America, New Yak, NY. a corpmafion of 5 even a short period of time, or even moderately elevated Delaware 7 temperatures durlng along period. N0 Drawing Filed Sept 27, 19 1, g 141,003 It IS therefore a principal ob ect of this invention to 2 Claims. (Ci. 75-174) provide an improved corrosion resistant alloy. Another object of this invention is to provide a thermally stable This invention relates to corrosion resistant alloys and 10 corrosion resistant alloy. Another object of this inven more particularly to alloys containing titanium and tantion is to provide an improved thermally stable and co rtalum having corrosion properties approaching those of rosion resistant alloy having corrosion resistant properties pure tantalum, and alos being thermally stable. approaching those of pure tantalum but which can be The excellent corrosion resistant properties of alloys produced at substantially lower cost. Another'object of containing titanium and relatively large percentage of tanthis invention is to provide a corrosion resistant alloy postalum are known. Such alloys are described in U.S. Patsessing high strength together with good ductility, and ent 2,964,399. In addition to binary alloys of titanium which is corrosion resistant and thermally stable. These and tantalum, alloys in which the tantalum is in part reand other objects of this invention will be apparent from placed by columbium are also described in this patent. I the following description thereof. 4 Such alloys are substantially less costly than pure tanta- This invention in its broad aspects contemplates corrolum but approach the corrosion resistance of tantalum in sion resistant alloys characterized by thermal stability, their ability to Withstand corrosive effects of solutions and consisting essentially of from 40 to 70% by weight such as boiling hydrochloric, sulfuric, phosphoric or oxtantalum, and a beta stabilizer selected from the. group alic acids. While these alloys do possess remarkable and consisting of vanadium, molybdenum, chromium, iron valuable .corrosion resistant properties, it has been found and manganese and mixtures thereof in amount from 2% that they are not thermally stable. When exposed to ternto 20% by weight, balance titanium. The thermal stabilperatures of the order of several hundred degrees Fahrity of the alloys of this invention is indicated by subenheit they tend to become brittle. This embrittlement stantial retention of ductility rafterexposure to tempera: can lead to catastrophic disintegration, and complete loss tures up to about 800 F. Optionally the alloys of this of their structural integrity. It is interesting to note in invention may include up to 2.5% by Weight ofgl p this connection that the reactions responsible for this em- 1mm, and additional advantages will be derived from its brittlernent appear to be functions of both temperature inclusion. A preferred range of beta stabilizing content and time, and while they are clearly evident after exis from 5% to 10% by weight within Which'theoptimum posure of such an alloy to a temperature of several hunadvantages provided by the beta stabilizer inclusion are dred degrees Fahrenheit in a relatively short space of obtained. Up to 15% by weight'ofcolurnbium may be time, the same embrittling effect occurs at lower temperemployed in the alloy 'of this invention to replace a atures after an extended period of time. Since, by their similar percentage of tantalum, the tantalum and columnature, corrosion resistant alloys are expected to provide bium being present in the aggregate within the range from often many years of service, even a slightly elevated tem- 40% to 70% by Weight and with tantalum content 35% perature during their normal useful life can produce un- 40 to 70% by weight. A particularly effective and desirable alloy composition consists essentially of about by Table 1 V CORROSION TESTS OF VARIOUS ANNEALED TITANIUM-TANTAL UM ALLOYS IN VARIOUS BOILING MEDIA artists Corrosion Rate, MilsPer Year Heat; Exposure i No. Composition Time,
Hours 20% 30% 3% Oxalic H01 H1504 H3PO4 ,Acid
48 0.1 48 0.6 48 0.3 48 0.7 Ti-40Ta-100b-2 168 4.8 '1i-40Ia10(lb-5V. 168 4.7 Ti40'la-10Cb-7V 48 8:1 Ti-40Ia-100b-1OV 24 0. Tl-40Ta-10Cb-10V 51 r 0.89 Ti-40Ta-10Cb-10V... 168 0. 45 Ti-40Ta-100b-10V... 336 0.34 Ti-40Ta-10Cb-10V.-. 672 0. 20 'Ii-40Ta-10Cbd2V... 48 -9.5 Tl-40Ta-10Cb-16V 48 4.9' Ti-40 Ta-10Cb-20V 48 6. 2 Ti-40Ta-10Cb-3Cr 24 2. 62 Ti 40'1a-100b 301;. 51 1. 21 TTa-10Ob 3Cr 168 0.75 T140Ta-10Cb-3Or. 336 0.41- Ti-40'Ia-10Cb-3Cr 672 0.25
weight of tantalum, about 1.5% by weight aluminum, about 8.5% by weight vanadium, and the balance titanium. Another very desirable specific alloy composition in which a portion of the tantalum content is replaced by columbium, consists essentially of about 40% by weight tantalum, about% by weight columbium, about 1.5% by weight aluminum, about 8.5 by weight vanadium, and the balance titanium.
Table l, preceding, shows the results of corrosion tests on a number of alloys whose composition is shown as percentages by weight of alloying ingredients, balance titanium. The ingredients for each alloy were melted in an arc furnace into a small ingotwhich was remelted several times to insure homogeneity. The remelted ingot was rolled to form sheet of thickness about 0.040 inch, andthe rolled sheet was annealed at 1400l500 F. for a period of /2 to 1 hour. Sections of sheet were cut to form coupons which were immersed in boiling acids of composition shown. Corrosion rates were calculated from weight loss.
Another group of alloys were similarly fabricated and tested for corrosion resisting properties by immersion in boiling HCl for 48 hours. The results of these tests are shown below in Table 2.
Table 2 FOR'IY-EIGHT HOUR CORROSION TESTS OF VARIOUS TITANI UM-TANTALUM ALLOYS IN BOILING 20% HO] 4 Table 2Continued FORTY-EIGHI HOUR CORROSION TESTS OF VARIOUS TITANIUM-TANTALUM ALLOYS IN BOILING 20% H01 Corrosion Heat No. Composition Rate,
Mils/Year Ti-50Ta-20V. 3. 6 1.7 3. 5 1.2 4. 2 41. 0 24. 0 9.8 32. 0 7. 9 T140'la-1OCb-10V-1.8Al I 17. 0 Ti-40Ta-l0Ob-12V-2JAL, 5. 8 Ti-40Ta-100b-1Fe 2. 6 'li-40'Ia-l0Cb-2 Fe. 14. 0 Ti-40Ta-l0Cb-4Mn. 5. 9 Ti-60Ta-8.5V-l.5Ai 0. 9 Ti-05Ta-8.5V-l.5Al 0. 4 Ti-GOTa-fiV-lAl 0. 9 Ti-50la-10Cb-6V-1A1 1. 2
I N.D.No determination. I Surface iiaw in specimen.
It will be seen from Tables 1 and 2 above that alloys of this invention show excellent corrosion resistant properties. Materials resisting corrosion to the extent that their corrosion rates are less than 50 mils per year in any given medium are rated as Class B, while those show- Corrosion ing less than 5 mils per year are rated as Class A. It is Heat f f evident by comparison with alloys of 50% titanium, and 50% tantalum, or 50% titanium, tantalum, and 3 6 10% columbium, that the corrosion resistance of these 014 alloys has not been materially affected by the addition of beta stabilizers according to this invention, and within the 0. 2 limits herembefore defined.
To determine thermal stability, the same types of alloys Ti-52Ta-3.5Cr-l.5Fe 7.2 tested for corrosion were fabricated to sheet in the same @kggggggiigg: 2:2 manner as those whose properties are shown in Tables 1 Ti'-58Ta-3.5Cr-l'.5Fe 3.5 40 and 2 (many of these being the same heats) and angijggggjgggffl fif ii nealed, exposed to elevated temperature and tested for '11-52'1a-s.5v-1.5A1.-- 1.3 strength and ductility. The sheets were annealed at gjgggjgzgxjgfi: 1400 F. or in some cases 1500 F. for /2 to 1 hour, air- Ti-58Ta-8.5V-1.5Al.- 2. 0 cooled, then heated for from 6 to 24 hours at mostly from $i328$1535i 3 j 3:; 500 F. to 800 F. Specimens were prepared and tensile g -soga-iogb-scgr n 10.5 strength (ultimate and yield) and elongation determined ,;3 g }3 e 2:2 on some, while on others bend tests were run to indicate i-g8%a-188lg---g ductility. Bend tests show the minimum bend radius, ex- I I '5, j: pressed as times the sheet thickness, which could be made l'gg% 'g6- i;- in a specimen Without cracking; such a test correlates iI I Io13o 1 Well with ductility indicated by elongation during tensile Ti-55Ta-8.5V-1.5Ai-0.2O1. 1.5 i e a T1 55Ta 8.5V 1 5M0 302 L9 test rig In each cas a specimen of the alloy s an Ti 4OTa wOb 5Gr 8 nealed was tested to provide a comparison with that which Ti-fioTa-lflv had been exposed to elevated temperature, and the re- THSO'Ia-IOV 0. e Q3 suits are shown in Table 3 below.
Table 3 THERMAL STABILITY OF VARIOUS TITANIUM-TANTALUM ALLOYS Tensile Properties Bend Heat No. Composition Thermal Treatment Properties,
UTS, YS Eiong., Min. '1 K s.i. K s.i. Percent 1,400 F., Hr. AC 88 so 24 1,400 F., 14 Hr. AC+800 F., 24 Hrs. AC 145 145 0 1,400 F., 2 Hr. AC 1,400 F., H1-. AC+500 F., 8 Hrs. AC 1,400 F., Hr. AC+600 F., 6 Hrs. AC 1,400 F., Hr. AC+800 F., 24 Hrs. AC 1,400 F., /5 Hr. AC 44 23 1,400 F., V Hr. A0+400 F., 0 Hrs. .40.- 100 04 is 1,400 F., Hr. -500 F., 6 Hrs. A01- 116 11s 10 1,400 F., V2 Hr. AC+800 F., 6 Hrs. 110.. 102 102 0 1,400 F., V; Hr. AO+800 F., 24 Hrs. AC--. 143 1,400 F., /z Hr. AC 100 as 31 1,400 F., Hr. AC+500 F., 6 Hrs. AC.... 125 8 1,400 F., Hr. AO+600 F., 6 Hrs. .40-.-- 139 1,400 F., Hr. AC 107 51 13 1,400 F., Hr. AC+600 F., 0 Hrs. AC .1 119 7 1,4o0r., /4H1.Ac. a 1,400 F., HI. AC+600 F., 96 Hrs. AC
Table fi -Continued THERMAL STABILITY OF VARIOUS TITANIUM-TANTALUM ALLOYS Tensile Properties I Bend Heat No. Oomposmon v I Thermal Treatment Properties,
UTS, YS, Elng., M111. T
K 5.1. K s.i. Percent Ti-40Ta-l0Cb-2V 1,400 F., 1 Hr. AG 103 50 18 Ti-40Ta-10Cb-2V 4 1,400 F., 1 Hr. AC+600 F., 6 Hrs. AC. 116 115 11. T1-40Ta,100b-5V 1,400 F., 1 Hr. AG 89 84 16 T1-40Ta-10Cb-5V 1,400 F., 1 Hr. AC+6OO F., 6 Hrs AC. 97 91 8 T1-40Ta-l0Ob-7V 1,400 F., Hr. AG 92 86 13 T1-40Ta-100b-7V 1,400 F., Hr. AC+800 F., 24 Hrs. AC. 93 87 13 Ti-40Ta-10Cb-12V 1,400 F., H1. AC 102 96 T140Ta-10Cb-12V 1,400 F., V; Hr. AC+800 F., 24 Hrs. AC. 103 100 I 15 T1-40Ta-10Cb-2OV 1,400 F., Hr. AC 119 111 11 T1-4OTa-1OOb-2OV 1,400 F., V, Hr. A0+s00 F., 24 Hrs. AC- 125 118 17 T1-40Ta-100b-3C1 1,400 F., 1 H1. AC 110 101 12 T1-40Ta-100b-3Cr 1,400 F., 1 Hr. AC+600 F., 6 Ers. AC. 111 109 9 T1-40Ta-10Cb-30r 1,400 F., 1 Hr. Ac+s00 F., 6 Hrs. AC- 115 112 6 T1-40Ta-10Cb-50r... 1,400 F., Hr. AC 93 91 16 TiTa-l0Cb-5Cr.. 1,400 F., Hr. AC+600 F, Hrs. AC 98 95 16 Ti-40Ta-10Cb-50r- 1,400 F., Hr. AC-l-600 F., 6 Hrs. AC 100 98. 15 Ti-EOTa-IOV 1,500 F2, H1. AC 106 102 15 Ti-Ta-10V 1,500 F., Hr. AC+800 F., 48 Hrs. A0. 111 106 7 T1-55Ta-5Cr 1,400 F., Hr. AC 121 117 8 Ti-Ta-5Cr 1,400 F., Hr. AC-l-GOO F., 6 Hrs. AC 124 120 8 Ti-40Ta-20Cb. 1,400 F., Hr, A Ti-40Ta-20Cb 1,400 F., Hr. AC+600 F., 24 Hrs. AC Ti-40Ta-20V 1,400 F., Hr. A
1,400 F., /2 Hr. AC-l-600 F., 24 Hrs. 140..-; 1,400 F., Hr. A 1,400 F., H1'.AO+500 F., 24 Hrs. AC 1,400 F., Br. .40.. 1,400 F., Hr. AC+500 F., 24 Hrs. AC Ti-40Ta-10Cb-12V-2.1A1 1,400 F., V; Hr. AC; 1 Ti-40Ta-100b-12V-2.1Al 1,400 F., V Hr. AC+500 F., 24 Hrs. AC Ti-35Ta-200b-10V-L8Al 1,400 F., Hr. A0 119 118 Ti-35Ta-20Cb-10V-L8Al 1,400 F., Hr. AC+800 F., 6 Hrs. AC 132 -128 Ti-35Ta-15Cb-10V-L8Al 1,400 F., V2 Hr. AC 115 110 Ti-35Ta-150b-10V-L8Al 1,400 F., V Hr. Ac+s00 F., 6 Hrs. AC 1- 119. 115 Ti-Ta-8.5V,-1.5Al 1,500 F., V Hr. AC Ti-60Ta-8 5V-1.5Al 1,500 F., V; Hr. AC+800 F., 0 Hrs AC Ti-Ia-8.5V-1.5Al 1,500 F., Hr. AC+800 F., 6 Hrs. AC..- Ti-60Ta GV-1A1 1,500 F., Hr. AC Ti-60Ta-6V-1Al 1,500 F., Hr. AO+800 F., 6 Hrs. AC Ti-50Ta-100b-6V-1Al 1,500 F., V2 Hr. A 4. Ti-50Ta-1OGb-6V-1Al 1,500 F., Hr. AC+800 F., 6 Hrs. AO Ti-40Ta-100b-1Fe 1,400 1 2% 11;.40 100 ,87 17 Ti-40Ta-100b-1Fe 1,400 F., V; Er. AC+600 F., 6 Hrs. AC 134 134 1 Ti-40Ta-l0Cb-2IFe 1,400 F., Hr. AC 113 110 17 Ti-40Ta-l0Cb'2Fe 1,400 F., H1. AC-l-GOO F., 6 Hrs. AO 119 117 1G Ti-40Ta-100b-2Fe 1,400 F., Hr. AC+800 F., 6 Hrs. AC 122 '118 9 Ti-40Ta-1OCb-4Mn 1,400 F., Hr. A0 116 111 16 Ti-40Ta-10Cb-4Mn 1,400 F., %,Hr. AC+600 F., 6 Hrs. A0 116 113 19 Ti-401a10Cb-4Mn 1,400 F., 4 Hr. AC+O F., 24 Hrs. AC 123 114 11, Ti-40Ta-10Cb-6W 1,400 F., Hr. AC Ti-40Ta-10Cb-6W 1,400 F., $4 Hr. AC+600 F., 6 Hrs. AC
Ti-40Ta-100b-6W 1,400 F., Hr..AC+8OO F., 24 Hrs, AC
Brittle, no yield. 2 Brittle. w r 1 The results obtamecl on the 50% tltamurn, 5 0% tanelement anhances the corrosion res1stance somewhat as talum alloy, as wellas the 50% titanium, 40% tantalum, Will be seen by reference to Table 2.
10% colu-rnbium alloys showed a markedloss in ductility Further tests were run to determine the thermal statilities of alloys containingf beta stabilizers, within the when these alloys were heated as low as 400 F. for 6 bility of alloys'of this invention under stress. This is a hours. and complete ,loss of ductility and glass hard brit- 50 characteristic that is valuable when material is employed tleness after being heated to 800 F.,for 24 hours. Heat to fabricate structural members which may be required T-284, which was made from an alloy containing 70% to operate under stress as well as at elevated temperatantalum, dropped'in elongation from 13% t0 7% after ture, as for instance autoclave parts. Specimens were heating for 6 hours at 600 F. In comparison, the ducannealed and then maintained under stress of from 25,000 to 70,000 psi; at temperatures of 500 F. and ranges hereindescribed, show little. significant reduction 600 F. for 150 hours. Comparison of ductilities, shown in ductility after heating up to 800 F. for 24 hours. by elongation percentages, indicated little difierence be- Those containing 5 to 10% beta stabilizers show exceltween specimens of alloys of this invention only annealed lent retention of ductility, considering, of course, the and after thermal stress treatment, While an alloy of limits of possible testing error. Inclusion of up to about 40% Ta, 10% Cb, balance Ti (Heat 9187) showed com- 2% aluminum tends to improve thermal stability, and plete loss of ductility. The results of these tests are inclusionof up to this amount of this optional alloying shown in Table 4 below.
. Table 4 THERMAL STRESS STABILITY OF'VARIOUS TITANIUM-TANTALUM ALLOYS Subsequent Tensile I I 3 Exposure Properties Heat 1 Composition Annealing Treatment Def.,
No. r Percent Stress, Time, UTS, YS, Eiong., K s.i. Hrs. K 5.1. K s.1. Percent Ti-40Ta-10cb- 25 150 Neg. 136 Ti-40Ta-10cb Tensile 44 28 Tl-40Ta-10eb-2V. 25 150 Neg. 131 9 Ti-40Ta-10cb-2V. Tensile 103 50 13 25 150 Neg 107 21 Ti-40Ta-l00b-5V Table 4Continued Annealing Treatment 1 1. 1 1 1 1 1. 1n1 1 1 1 1 1 1 1 1 1 Ll inl l l l l inl l 1 1 1 1 1 1 1 1 1 1 1 1 1 1 n n n n u n n 11 n AAM u N n fir n m .M 1.11 1 RD N. v wmw new haul M m 6 bob bloom. mmb Mb w CCCVV CCOCO Vvv 0 CO 0 OOOOOCCOOOOO ..0.5.5.VV0 00 a ammawmwwmawwww aawaaw awn w wwwwwwawwwww Manama WM M HMMMMMMHMMMM HM T TTTTTTTTTTTT TTflTTT TT a a. mafi MMT TTTTTT columbium master alloy canbe used in its Its corrosion resistance is not appreciably ive the
Adequate corrosion It is extremely than 70% are employed, the corrosion resistant properties may correspond closely to those of pure tantalum but at 75 the same time, due to increased alloying and processing Bend, Min. '1
der conium aplarge measure responsible for the corrosion Elong.,
Percent hen a comhereby. The
Ys, K 5.1.
lum and no columit may advantageously be employed un U'rs, K st.
tantalum is employed, a large Table Continued or, if part of the tantalum is replaced the tantalum content should be at least If more than 70% If percentages of tantalum higher Mechanical Properties X6; 2Iii6ifrIIII The alloy containing columbium replacing part of the tantalum has the advantage of reduced cost w bined tantalumproduction.
than the alloy containing tanta and The amounts of the various alloying constituents in thef positions of this invention are critical to obta expensive material.-
ditions in which is may be exposed to less corros media than those used for test results.
benefits and desirable properties imparted t tantalum content in combination with the titan pears to be resistant properties of the alloys.
resistance will not be obtained if the tantalum content is less than 40% by columbium,
part of the extremely desirable low cost advantage of t alloys of this invention will be lost.
significant that the alloys of this invention provide corrosion resistant properties approaching those of pure tantalum, yet contain 70% or less of tantalum, which is very tantalum, num, balin this case 10% gagi g tantalum content has been replaced with colum- 3% Oxalic Acid Bend, Min.l
3% Oxalic Acid combination inum, bal- 30% H3PO4 Elong., Percent rosion resistance and mechanialloys, before and after thermal in Table 5 below.
20% HCl UIS, YS, Ksi.
20% HCl- 1 Brittle; broke outside gage length.
sistance and thermal stability contains 8.5% vanadium, 1.5% alum Representative cor Table 5 ALLOY-50% Ta, 8.5% V, 1.5% A1, BALANCE Ti Mechanical Properties ALLOY-40% Ta, l0% Ob, 8.5% V, 1.5% A1, BALANCE Ti A preferred alloy showing an excellent Year (48 hour test)..
year (48 hour test)..
of corrosion re 50% tantalum, 8.5% vanadium, 1.5% alum ance titanium. A similar alloy contains 50% 10% columbium,
ance titanium and it will be noted that of the bium. v
cal properties of these exposure, are tabulated Boiling..
Corrosion Resistance, Mils per As Annealed---" After 800 F. for 24 hours Boiling Corrosion Resistance, Mile per costs, the more complex compositions may show little, if any, significant cost advantage.
The percentages of beta stabilizing elements are critical to obtain the disirable stability characteristics without affecting to an appreciable degree the excellent corrosion resistant properties of the alloys. Less than 2% beta stabilizer will not provide suflicient increase in thermal stability to be appreciable or of practical importance, and more than 20% beta stabilizer will adversely affect the corrosion resistance and in addition, some of the mechanical properties. A small amount of aluminum within the limit stated will improve the corrosion resistance, although the reason for this effect is not precisely known. In addition, the small amount of aluminum contributes to providing thermal stability in the alloy since it will to some extent reduce the tendency for precipitation of the omega phase which has a marked hardening efi'ect on the beta matrix. More than 2.5% of aluminum will tend to more strongly stablize the alpha phase and reduce the beneficial effects of inclusion of beta stabilizers as hereinbefore described.
The alloy of this invention may be produced by any convenient method in which the constituents are rendered molten to provide an ingot of homogenous alloy composition. Arc melting procedures may be employed, and the titanium, tantalum and other alloying constituents may be pressed into compacts and these compacts assembled into an electrode which can be melted into a cold mold crucible by the well-known consumable electrode arc melting process. It should be pointed out, however, that a homogenous ingot is necessary to obtain uniform properties, and the proper and desired effect produced by the various alloy constituents. It will be appreciated that titanium and tantalum have substantially different melting points and more than normal difficulty may be encountered in producing an ingot which is free from unmelted inclusions of the, higher melting point tantalum metal. Use of tantalum in relatively finely divided powdered form, so as to obtain an initial relatively good dispersion of this material, will be helpful in producing homogeneous materials; and in addition, remelting of the ingot perferably several times will be found also effective to produce acceptable homogeneity.
The alloys of this invention possess outstanding corrosion resistant properties as will be evident from the data presented herein. At the same time the thermal stability, as indicated by retention of ductility after exposure to temperatures up to 800 F., will be satisfactory for applications involving exposure of products fabricated from these alloys at such elevated temperatures for a reasonable period of time, and also indicates a substantial immunity from thermal instability at temperatures of the order of those normally encountered in boiling aqueous solutions for an extremely long life period. It will be appreciated by those skilled in the art that an alloy of this invention can be used for long periods of time without fear of embrittlement under corrosive conditions at elevated temperatures, as for example, when employed as structural or lining materials in autoclaves, and similar relatively high temperature and pressure equipment, as well as being useful at temperatures encountered in contact with aqueous solutions even up to their boiling point more or less indefinitely.
The alloys of this invention are characterized, in addition, by substantially higher tensile strength than shown by pure tantalum or by the previously known alloys of V tantalum and titanium.
Inclusion of a beta stabilizing element markedly increases the yield strength and tensile strength of the alloy. This makes it possible for thinner and lighter structural or lining members to be employed While retaining similar strength and corrosion resistant properties. It will also be found that the alloys of this invention are considerably lighter than the pure tantalum which they are capable of replacing in many applications; and this is responsible for production of a greater volume of fabricated material per pound; thus further reducing the cost of the alloy in useful form. It will be evident that a. pound of an alloy according to this invention will provide substantially more sheet of a given thickness than can be obtained from a pound of pure tantalum. The
' other, less costly, elements.
1. An alloy formed by melting its constituents characterized 'by resistance to corrosion by HCl indicated by a corrosion rate of less than 10 mils per year in boiling 20% HCl, 48 hour test, and by thermal stability indicated by substantial retention of ductility after exposure to temperatures up to about 800 F. consisting essentially of:
(a) about 40% by weight tantalum,
(b) about 10% by weight columbium,
(0) about 1.5% by weight aluminum, and
(d) about 8.5% by weight vanadium,
(e) balance titanium.
2. An alloy formed by melting its constituents characterized by resistance to corrosion by HCl indicated by a corrosion rate of less than 10 mils per year in boiling 20% HCl, 48 hour test, and by thermal stability indicated by substantial retention of ductility after exposure to temperatures up to about 800 F. consisting essentially of:
(a) about 50% by weight tantalum, (b) about 1.5% by weight aluminum, and
Reactive Metals V, 2 reprinted from Metallurgical Society Conferences, Proceedings of the Third Annual Conference sponsored by Niagara Frontier Section in cooperation with The Metallurgical Society, Aimme, Buffalo, New York, May 27-29, 1958, Interscience Publishers (pages 497-499 relied upon).