Titanium and zirconium alloy system consists of a continuous series of random substitutional solid solutions of solvent and solute atoms. Titanium scatters thermal neutrons in the opposite phase from those scattered by zirconium, the scattering amplitudes being: bTi=−0.38×10−12 cm and bZr=0.62×10−12 cm. An alloy containing 62 atomic percent titanium and 38 atomic percent zirconium is developed that gives no coherent scattering reflections in its neutron diffraction pattern, and is extremely useful in constructing devices in which scattering of thermal neutrons is not desired. Based on negative and positive scattering amplitudes of different isotopes of the same element for thermal neutrons, development of isotopic alloys is suggested.