82 Prakt. Met. Sonderband 38 (2006) 
to generate more knowledge about the effectivity of other hardening mechanisms than Th 
particle strengthening and their stability during hot deformation in order to run a highly ele 
efficient production of molybdenum alloys. The results should lead to new considerations the 
which will help to improve and design the properties needed in thermal loaded the 
applications. Since their commercial demand is fairly low there are only a few creep data 15 
of solid-hardened molybdenum alloys available in the literature [1]. me 
te; 
in\ 
2. EXPERIMENTAL DETAILS AND SPECIMEN PREPARATION We 
Or 
The molybdenum alloys were processed by powder metallurgy by the PLANSEE process up 
route. In a first step MoO2 powder was mixed with TiH2, ZrH2 and graphite in case of TZM. thi 
For the Mo-Ti alloy only MoO, and TiN was used. Different powder mixtures were cold te: 
isostatic pressed and sintered at temperatures above 1800 °C for more than 5 hours. The the 
global chemical composition of the as sintered material determined by ICP (spectroscopy Fir 
with inductive coupled plasma) is listed in table 1. CC 
9° 
Table 1: Chemical composition of Mo-Ti and TZM after sintering [ppm] mi 
a MM Zr C OÖ 
TZM 47990 | 1055 243 
M-. 4700 0 61 <5 
The as sintered material was forged and completely recrystallized. The prepared rods 
were hot rolled at 1400 °C (0.58 Tn) to a deformation degree ¢, (logarithmic) up to 1.55. 
All manufactured specimens were prepared for optical and scanning microscopy by 
automatically grinding and then diamond abrasive polishing down to 1um. Finally, the 
microsections were electropolished using the Struer’s electrolyte A3. The microsections 
for optical microscopy using the differential interference contrast (DIC) were etched with 
Murakami, see figure 1a. By means of the DIC technique the deformation substructure 
inside the specimens is clearly detectable in figure 1b (elongated grains and subgrains). 
Fix 
IC 
a) Bright field image b) Differential interference contrast 
(DIC) 
Fig. 1: Optical micrographs of the microstructure of hot rolled molybdenum alloy TZM