Evolution of Microstructure and Mechanical Properties of Ni/Al Composites during ARB

Ni/Al composites with Ni ∶Al volume ratio of 2 ∶1 were prepared by cumulative rolling（ARB） method. The effect of work hardening on the thinning rate of Ni particles, the ratio of width to thickness, the contact degree of NiAl and the hardness of the composite was studied. The results show that, when the number of rolls n≤5, the composite material is mainly distributed in layered structure, less fracture occurs, the thickness of Ni particles decreases quickly, and the contact degree of NiAl increases quickly. When the number of rolling passes n＞5, the Ni layer fracture increases, the thinning rate of Ni particles gradually slow down, the NiAl contact increases slowly, the width to thickness ratio gradually decreases and the degree of fragmentation increases. The mathematical equations of the thinning ratio of Ni particles（THK/THK₀）, Ni Al contact S and rolling pass n are established. The mathematical fitting equations of HV_Ni, HV_Aland HV_Ni/Alwith rolling pass n are established,the hardness of HV_Ni, HV_Aland HV_Ni/Alincrease with the increase of roll pass n, and the fitting equations of HV_Niand HVAl show a linear increasing trend. However, HV_Ni/Algradually approaches HV_Alwhen the number of rolling passes is less than 7,and HV_Nigradually approaches HV_Niwhen the number of rolling passes is more than 7, which is due to the increase of deformation and uneven distribution of Ni components, leading to the abnormal increase of hardness.