Properties and structure of the shape-memory melt spun CuAlNiMnTi(Zr) ribbons

The CuAlNiMnTi(Zr) alloys with 0-5% Mn and up to 1% Ti or Zr (in wt.%) were cast using melt spinning method at linear wheel rate 3.5-31 m/s. Fine grai n ribbons with good shape memory effect within 0 200 degreesC were obtained without an additional heat treatment. The microstructure was analyzed usin g optical, scanning and transmission electron microscopy, while their mecha nical properties were examined in tensile test using Instron TT-DM machine. The martensite transformation in ribbons was found to be depressed to lowe r temperatures with decreasing grain size accordingly to the equation Delta M = k(.)d(-1/2) The addition of grain refiners like Ti or Zr decreased grai n size even to sub micron range. At the highest of applied linear wheel rat e of 30.6 m/s a dissolution of Ti within beta matrix was observed, while at lower rates the cubic Cu2TiAl type precipitates were formed. The ribbons c ontaining CuAlNi 2wt.%Mn0.4wt.%Ti showed best mechanical properties.