PURPOSE: To increase the strength of a joint part and to relieve stress by using a metallic material of which the coefft. of thermal expansion in a prescribed temp. range is a specific value or below and the elastic modulus at an ordinary temp. in a specific value or below to join a hard and brittle material of which the coefft. of thermal expansion is a specific value or below.

CONSTITUTION: The metallic material for joining consists of Zr, Nb, Ti, V, Hf or the alloy thereof of which the average coefft. of thermal expansion in a 20W500°C range is ≤10.5×10-6/°C and the elastic modulus at the ordinary temp. is ≤14,500kgt/mm2. Such metallic material for joining is used for joining of the hard and brittle material of which the average coefft. of thermal expansion in a 20W500°C range is ≤8×10-6/°C, for example, Si3N4, SiC, etc. The joint part having the high joint strength and small joint strain is thus obtd.