Metallographic Analysis of Lamellar Structure of Titanium Alloys 
Ti-Al-Mo-Zr Using Both Optical and Electron Microscopy 
C. Dumitrescu, M. Dobrescu, L. Gavrila, University Politehnica Bucharest (RO) 
Introduction 
Alloys based on titanium from Ti-Al-Mo-Zr system are of practical importance due to their low 
density and enviromental resistance at elevated temperature. 
The primary purpose of the study is to analise the lamellar structure of titanium alloy (Ti-6Al-3,5 
Mo-1,7Zr) in order to clarify how takes place the precipitation of « phase (fine or coarse grains) 
and the influence on mechenical proprieties (1). 
Experimental 
Researches were done on Ti6Al3,5Mo,1,7Zr alloy using a scanning electron microscop (SEM) 
PHILIPS - 515. 
Quantitative Image Analisys assisted by computer was also neceessary to know the thikness of a 
lamellar phase and the amount of o and § phases. For these investigations we used a Nepoht — 21- 
Microscop, Matrix Vision PC Image, colour camera CCD and an Intel Pentium Computer. 
Results 
Heat treating conditions for Ti-6Al-3,5Mo-1,7Zr alloys are shown in Tabel 1 (2) 
Table 1 — Heat treating conditons for Ti-6Al-3,5Mo-1,7Zr alloy 
ST Mechanical | 
caracteristics 
Sample Heat treatment TS E 
Se _ MPa % 
Pr7 | 1h-1050°C, WQ + 4h -650°C, AC ‚ 5 1250 7 
Pr8 1h - 900°C, WQ + 4h - 650°C, AC 1120 | 12 
'Pr9 1 1h-900°C — 1 h—750°C, AC +4 h - 590°C, AC 1120 | 12 
‚Pr 10 1h-950°C, AC —>1h-850°C, WQ+4h-59°C, AC |, 1210 | 12 
| Pr 11 1 h-1050°C, AC —> 1 h—900C, WQ + 4 h-650°C, AC Lo 1200 | 8 
i Pr12 1 1h-900°C, AC +4 h-590°C, AC | 120 12 
WO — Water quenched; AC — air coled: Ts — tensile strength; E - elongation 
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