Prakt. Met. Sonderband 41 (2009) 95
a few hun- step in order to ensure that abrasive particles are neither carried over to the next step nor embedded
aner. A lit- in subsequent steps. All polishing operations were performed such that the sample movement is in
ler is mate- the direction opposite to that of the rotating disc. The etched surfaces were rinsed with alcohol,
alized and cleaned in an ultrasonic bath at room temperature, further rinsed with alcohol and then air dried.
ce the out- } Co Co . . .
oach which Table 2. Final polishing (etch-polishing) step. Hand processing at disc rotating speed; 180 rpm.
»Cu ternary Trial Fabric Agent ~ Time
! Long fibre soft 100 ml Al,Os - suspension (0.06 5 — 10 min
(OP. Chem.) um) with light pressure in the
+2 ml H,0, + 5g citric acid direction normal to sample
surface
Long fibre soft 100 ml AlL,O; - suspension (0.06 2 —4 min
(OP. Chem.) um) + 10 ml H,O de-ionized + with light pressure in the
d called mn 0.5g KCN* direction normal to sample
t allows for surface
o ine # KCN is a strong poison. Precautions for handling and storage must be followed.
C) machine
I the Spect- Table 3. Etching condition for trials 1 and 2.
ectional di Trial DS a Solution (following Ref. [6]) Remark I
3 0 ial 1)100 ml H,O (de-ionized) Etching at room tem-
at treatment 100 m! H,O, perature for 30 sec to
0 °C for 15 32 g iron (iii) chloride 1 min
cturer — De- 1) 100 ml H,O (de-ionized) Solution 1 and 2 are
p). The heat 10 ml Ammonium peroxide mixed in equal parts be-
2) 100 ml HO (de-ionized) fore use.
procedures. 10 ml KCN Etching at room tem-
rection ba perature for 10 min
) ensure tha
vhat similar The prepared sections were imaged using an optical light microscope model Zeiss Axiovert 200
ese two ap- MAT. Revealed structures were viewed in both bright field (BF) illumination and differential inter-
out different ference contrast (DIC) illumination modes. The DIC has an advantage of enhancing the depth of
focus making it possible to bring all parts of an illuminated area into focus irrespective of sample
| thickness effects. The porosity (obtained from unetched images) and grain size in the specimens
rocessing by was determined using a reduced grayscale spectrum method and the linear intercept method, respec-
CC — tively. The hardness state in the micro specimens was determined by microhardness test method.
Time - First the micro specimens were polished in the length-wise direction using metallographic methods.
15 min This ensures that there is access to a wide test area on the micro specimen and also that the test sur-
I min face is flat and free of relief. A Vickers indentor tester Shimadzu HMV 2000 with a load of 50 g
pe was used to obtained data at intervals of 200 um along the length of the test sample.
sec
10 — 30sec
2-5 min
preparation
ach grinding
J
3
