A reinforced composite material, having isotropic thermal expansion properties and a low coefficient of thermal expansion over at least the temperature range of from about 0.degree. C. to at least about 150.degree. C., which composite material comprises in combination a first continuous phase comprising a three dimensional preformed bonded powder material reinforcement, including a bonding agent, and in which the bonded powder material is chosen from the group consisting of zirconium tungstate, hafnium tungstate, zirconium hafnium tungstate, and mixtures of zirconium tungstate and hafnium tungstate, and a second continuous phase matrix material chosen from the group consisting of aluminium, aluminium alloys in which aluminium is the major component, magnesium, magnesium alloys in which magnesium is the major component, titanium, titanium alloys in which titanium is the major component, engineering thermoplastics and engineering thermoplastics containing a conventional solid filler.