a method is provided for alleviating the stress damage in metallic matrix composites , such as laminated sheet or foil composites , wherein discontinuities are positively introduced into the interface between the layers so as to reduce the thermal stress produced by unequal expansion of the materials making up the composite . although a plurality of discrete elements could be used to form one of the layers and thus carry out this purpose , the discontinuities are preferably produced by simply drilling holes in the metallic matrix layer or by forming grooves in a grid pattern in this layer .