an intravascular guide wire having two core materials joined together without the use of a connector tube or sleeve , the core materials being stainless steel and psuedoelastic metal alloy , nitinol . the core materials are joined to each other through an intermediate transition piece made essentially of nickel , which is welded on either side to the two core materials . in alternative embodiments , the intermediate piece may have different shapes to provide different strengths and advantages as may be required .