Deformation Microtwins

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=82 BGCOLOR="#888888" TEXT="#080000" bgproperties="fixed" background="048cb0b1epaffc.gif"> <div> <B>Deformation Microtwins</B></div> <bR> <div> </div> </td> </tr><tr> <td valign="top" width=210 BGCOLOR="#555555" TEXT="#080000"> <div> <A HREF="id18.htm" TARGET="_top" TITLE="Deformation Microtwins"><U><B>Introduction</B></U></A></div> <div> <A HREF="id18.htm" TARGET="_top" TITLE="Deformation Microtwins"><U><B>Experimental Procedure</B></U></A></div> <div> <A HREF="id18.htm" TARGET="_top" TITLE="Deformation Microtwins"><U><B>XRD</B></U></A></div> <div> <A HREF="id18.htm" TARGET="_top" TITLE="Deformation Microtwins"><U><B>TEM</B></U></A></div> <div> <A HREF="id18.htm" TARGET="_top" TITLE="Deformation Microtwins"><U><B>Discussion</B></U></A></div> <div> <A HREF="id18.htm" TARGET="_top" TITLE="Deformation Microtwins"><U><B>Conclusions & Acknowledgement</B></U></A></div> <bR> </td> <td valign="top" height=398 BGCOLOR="#EEEEEE" TEXT="#080000"> <div> <I><B>Abstract</B></I></div> <div> Microstructural studies involving texture analysis and transmission electron microscopy have been carried out in batch and continuously cast Cu-Ni-Mn alloys. The continuously cast alloy showed an inhomogeneous development of texture due to its initial {001}<100> as-cast orientation. At heavy deformations, there is a localized transition of deformation mechanism from cross slip to twinning due to inhomogeneous distribution of stresses. Even though the macro-texture can be described as copper-type, micro diffraction revealed the presence of microtwins of less than 0.02 µm in thickness, lying on {111} traces. The misorientation between adjacent microtwinned regions is about 5º around the 110 pole. The existence of a high density of defects inside the microtwins was confirmed by bright field observations and by the elongated spots in the selected area diffraction pattern.</div> <bR> <div> Papers published from this work:</div> <bR> <div> J.R.T. Lloyd,<B> P. Caceres</B>, B. Ralph and P. Brondsted; "Observations of Substructure Associated with Fatigue in a Low Alloy Steel", <B>1985</B>, Scripta Metallurgica, v.19, pp.1475-1480.</div> <div> <B>P.G. Caceres</B> and R.D. Garwood, “Micro Beam Orientation Determinations in Highly Deformed Cu-12.5%Ni Alloy”, Proceedings of the 43rd Annual Meeting of      the Electron Microscopy Society of America, Ed. G.W. Bailey, San Francisco, <B>U.S.A., 1985.</B></div> <div> <B>P.G. Caceres-Valencia;</B> "Development of Deformation Microtwins in Cu-Ni-Mn Continuously Cast Alloys", published in the Materials Science and Technology, September <B>2005</B> Conference Proceedings, Pittsburg, <B>U.S.A.</B> </div> <bR> <bR> <bR> <bR> <bR> </td> </tr></table></body>