K-CARBIDES PRECIPITATION IN TWO HIGH MANGANESE ALLOYS
Two high Mn alloys marked A (24Mn-1.2C-12Al) and B (28Mn-0.7C-8.6Al) were laboratory hot rolled. After rolling in material A coarser k-carbides were detected, sporadically on the austenite grains boundaries and more frequently on the ferrite ones. Reason was un-balanced Mn a C contents in superposition with the rolling deformations and finishing rolling temperature of 950°C. Hardness corresponded to 432HV30 on average. Using light microscope no carbides on grains boundaries were observed in B both after rolling and followed aging at 500°C/6´. After 6 minutes of aging the hardness of B was approx. by 9 % higher unlike the rolled state. The X-ray analysis nucleation of nano-size kcarbides confirmed. After aging of B at 500°C/30´ and/or 60´some coarser k-carbides were detected on ferrite-austenite boundaries and/or austenite-austenite interface. The hardness went up and corresponded to 343 and/or 350HV30. From the X-ray and microstructure analyses follows the 30´ and/or 60´ dwell supported both very fine and coarser k-carbides precipitation. The calculated stacking fault energies (SFE) of both materials complete all solution. The A showed by 9 mJ.m -2 higher SFE than the B. In the A alloy lower Mn content and higher Al one resulted to 2.8 times higher ferrite volume fraction in comparison with the B alloy.
Phase constitution and lattice parameter relationships in rapidly solidified (Fe0.65Mn0.35)0.83 Al0.17-xC and Fe3Al-xC pseudo-binary alloys
A quasi-equilibrium temperaturevs carbon-concentration phase diagram of rapidly solidified pseudo-binary (Fe0.65Mn0.35)0.83Al0.17-xC alloys was determined after heat treatment in the 823 to 1323 K range. Lattice parameter relationships of rapidly solidified (Fe0.65Mn0.35)0.83Al0.17-xC and Fe3Al-xC alloys in the ferrite, austenite, and perovskite carbide phases were established as a function of the carbon concentration. This study shows that when a high concentration of carbon is present in the alloys a perovskiteL′l2 carbide is formed directly from the rapid solidification process. It is established also in this study that the carbon atom contribution to the lattice parameter increase in the fcc-based cubic crystal is greater in the disorderedγ-phase than in the ordered (L′l2 structure)κ-phase.
Britain and the Problem of International Disarmament: 1919-1934
Acknowledgements 1. Introduction 2. The Concept and Context of Disarmament, 1919-1934 3. The Human Element 4. The Lloyd George Coalition Government, 1918-1922 5. The Conservative Governments, 1922-1923, and the First Labour Government, 1924 6. The Conservative Government, 1924-1929 7. The Labour Government, 1929-1931 8. The National Government, 1931-1934 9. Conclusion Bibliography