The microstructure, texture and grain refinement mechanism of cold-rolled AlNdTi alloy target: Large deformation promotes dynamic recrystallization

In this work, the high pure AlNdTi alloys ($>$ 99.99 wt%) were rolled to a total of 20 %, 40 %, 60 % and 80 % thickness reduction with a reduction of 2 mm during each pass by a two-high mill rolling machine with the roll diameter of 500 mm. Moreover, a comprehensive investigation was carried out to study their microstructure, phase distribution, misorientation, texture and microhardness properties. As a result, with the cold-rolled deformation increasing, the grain size of AlNdTi alloy reaches its minimum value of 18 μm at 80 % deformation. Meanwhile, the development of phase distribution shows that the reticular distribution state of $\alpha$-Al₁₁Nd₃ remains unchanged, but some microcracks appear on its surface after large rolling deformation. In addition, the misorientation results show that proportion of recrystallized grains in 80 % rolled AlNdTi alloy is as high as 43.2 %, while the proportion of deformed zone is only 12.5 %. Moreover, the percentage of high-angles of 80 % rolled sample is 34.2 % and the average misorientation angle is 16.8 $°$. Besides, the subgrains with the diameter of 1∼2 $\mu$ m and recrystallized grains with the diameter of 3∼5 μm observed by TEM provide direct evidence that dynamic recrystallization occurred in high-purity AlNdTi alloys during rolling deformed process. And the grain refinement mechanism was analyzed and discussed. Furthermore, the texture development of AlNdTi alloy with various rolling deformation was analyzed in detail. Besides, 80 % rolled AlNdTi alloy has the largest hardness of 45 HV, while the microhardness of as-cast AlNdTi alloy is only 23 HV. In a word, these results can provide a new perspective on the control of microstructure, phase distribution, texture evolution, etc. of cold-rolled AlNdTi alloy target in liquid crystal display industry. Moreover, it is beneficial for clarify the generation of dynamic recrystallization on the plastic deformation behavior of this alloy target.