Materials Science Forum Vols. 192-194 (1995) pp 525-534 © (1995) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/MSF.192-194.525 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 134.147.174.111, UB Bochum, Bochum, Germany-12/08/13,17:33:37)