Pure copper with different fraction of nonequilibrium grain boundaries were achieved by friction stir processing (FSP) under air, water and liquid nitrogen cooling conditions. Tensile behaviors at room temperature exhibited significant difference for above three cases involving different fraction of nonequilibrium grain boundaries. The case with nitrogen cooling showed better combination of strength and elongation for the largest fraction of high energy nonequilibrium boundaries, which contribute to emit dislocations from grain boundaries and suppress grain boundary sliding. Fully relaxed grain boundaries in air cooling samples can suppress the grain boundary sliding and dislocation emission causing high stress and very low elongation. However, appropriate relaxed grain boundaries in the water cooling samples will promote grain boundary sliding and the increase of elongation. The grain coarsening during tensile deformation was observed in those samples with nonequilibrium grain boundaries and will increase elongation and cause work softening behavior of these samples.

通过在空气，水和液氮冷却条件下进行摩擦搅拌处理（FSP），可以得到具有不同比例的非平衡晶界的纯铜。对于上述三种情况，室温下的拉伸行为表现出显着差异，涉及不同比例的非平衡晶界。氮气冷却的情况表明，对于最大比例的高能非平衡晶界，强度和伸长率的组合更好，这有助于从晶界发出位错并抑制晶界滑动。空冷样品中完全松弛的晶界可以抑制晶界滑动和位错散发，从而导致高应力和极低的伸长率。然而，在水冷样品中适当的松弛晶界会促进晶界滑动和伸长率的增加。在那些具有非平衡晶界的样品中观察到了拉伸变形过程中的晶粒粗化，这将增加延伸率并导致这些样品的工作软化行为。