The Cu-1.6wt%TiB2 alloys have been prepared by combining mechanical alloying and heat treatment. The relationship among microstructure evolution, mechanical property and in situ reaction mechanisms in synthesizing Cu-1.6wt%TiB2 alloys was investigated. It is shown that the temperature 750 degrees C measured by DSC can cause the occurrence of in situ reaction between B and Ti elements in the Cu-B-Ti alloy powders ball milled for 40 or 60 h; An upward trend of the hardness appears after heat treatment at 700 degrees C, and the highest value reaching 335HV, but a downward trend appears after heat treatment at either 500 degrees C or 900 degrees C; Many coarse B particles were formed in the copper matrix after heat treatment at 500 degrees C, the number and size of the formed B particles significantly increases with increasing time, but many reaction boundaries (or TiB2 films) and finer TiB2 particles can be formed after heat treatment at both 700 degrees C and 900 degrees C. The different in situ reaction models between Cu-B and Cu-Ti alloy micelles with different distribution levels were established and analyzed. (C) 2012 Elsevier B.V. All rights reserved.