Method for joining metal parts

A method for joining a first metal part with a second metal part, the metal parts having a solidus temperature above 1100° C., the method comprising:

• applying a melting depressant composition at least on a surface of the first metal part, the melting depressant composition comprising:
• a melting depressant component comprising at least 25 wt % boron and silicon in total for decreasing a melting temperature of the first metal part;
• and
• optionally, a binder component for facilitating the applying of the melting depressant composition on the surface;
• bringing the second metal part into contact with the melting depressant composition at a contact point on said surface;
• heating the first and second metal parts to a temperature above 1100° C., said surface of the first metal part thereby melting such that a surface layer of the first metal part melts and, together with the melting depressant component, forms a molten metal layer that is in contact with the second metal part at the contact point;
• and
• allowing the molten metal layer to solidify, such that a joint is obtained at the contact point,
• wherein a source of the boron comprises a boron compound selected from any of the following compounds:
• titanium diboride, boron nitride and/or combinations thereof.