A technique for preparing thin foils of ti and ti alloys for transmission electron microscopy
- PDF / 920,116 Bytes
- 2 Pages / 612 x 792 pts (letter) Page_size
- 25 Downloads / 192 Views
are then made using the window method with an acetone-soluble lacquer to mask edges of the specimen. An electrolyte consisting of 5 pet H2SO4 by volume in methanol is the final thinning solution. Conditions for preparing thin foils are listed in Table I. The electrolyte is s t i r r e d continually during the thinning process, while the specimen (anode) remains 2 to 3 cm away from the platinum cathode. After thinning, the specimen is washed in methanol. Because of a residue that f o r m s on some of the foils, the following cleaning procedure is needed. F r o m the methanol the foil is washed in H20 a few seconds, then given a 30 see wash in concentrated HNO3 acid. Upon removal from the acid the foil is washed in HzO, then methanol and finally i m m e r s e d in ethyl alcohol during cutting to E.M. size specimens. Figs. 1, 2, and 3 are typical mierographs of foils made using the above technique. Compositions of the alloys are expressed in wt pet. Fig. 1 is a micrograph
A Technique for Preparing Thin Foils of Ti and Ti Alloys for Transmission Electron Microscopy R. A. SPURLING Many techniques have been used in recent years for thin-foil preparation of Ti and Ti alloys. Both chemical 1'2 and electrolytic s-~ thinning methods are c u r rently in use, but the preference appears to be electro-thinning. The chemical thinning solutions g e n e r ally are various concentrations of HNO3-HF while p e r c h l o r i c - a c i d containing solutions are used for electro-thinning. Cooling the solutions (chemical or electrolytic) is the key to successful foil making of Ti and Ti alloys because of a better controlled polishing rate and a minimization of H2 pick-up. 3'6 Consistency in thinning single phase (c~ or 13) alloys using the existing thinning solutions can be maintained but when thinning two phase alloys one of the phases generally is preferentially attacked. The technique described below was developed for thinning two phase (~ +/3) structures and is equally efficient for either or/3-phase samples. The electrolyte has the advantage over other solutions in that it polishes more r a p idly and is less hazardons than the perchtoric acid solution. Specimens to be thinned a r e secured to a fiat block by an alcohol-soluble wax, then mechanically ground through 600 grit SiC abrasive to a thickness of 0.0025 cm. Care must be taken in handling specimens in this step so as not to introduce deformation. Thin foils R. A. SPURLING is Metallographer, Science Center, Rockwell International, Thousand Oaks, CA 91360. Manuscript submitted February 17, 1975. 1660-VOLUME 6A, AUGUST 1975
Fig. 1 - - T r a n s m i s s i o n e l e c t r o n m i c r o g r a p h of T i - 5 AI s i n g l e c r y s t a l a n n e a l e d at 1125 K and s t r a i n e d 2 pet at 600K.
Fig. 2 - - T r a n s m i s s i o n e l e c t r o n m i c r o g r a p h of T i - 4 0 V + 250 p p m O 2 s o l u t i o n t r e a t e d and aged 675 K / 1 week. METALLURGICAL TRANSACTIONS A
Discussion of "Thermodynamicsof t3,-NiZn and ot-NiZn Phases"* R. P. ANANTATMULA In a recent communic
Data Loading...
