铸造之前,直接把变质剂加入到熔体中去通常能细化铸铝的晶粒。这些变质剂起着非均匀成核作用,产生细小、等轴的晶粒组织。虽然已经研究过许多种不同的添加剂,但其中效果最好的是使用钛基或钛—硼基变质剂,这些变质剂是做为合金硬化剂被加入到熔体中去的。尽管对细化机理尚存在着某些争论。但(?)性生成物是包晶化合物 Al_3 Ti 及硼的存在能加速这种化合物的生成这一结论却已为大家所公认。许多研究者还研究了铌添加剂的影响, Prior to casting, adding modifier directly to the melt typically results in refinement of the cast aluminum grains. These modifiers act as non-uniform nucleation and produce fine, equiaxed grain structures. Although many different additives have been studied, the most effective of these is the use of titanium-based or titanium-boron-based modifiers that are added to the melt as alloy hardeners. Although there is some debate on the refinement mechanism. However, it is generally acknowledged that the formation of (?) Sex products is the result of the presence of the peritectic compound Al3 Ti and boron to accelerate the formation of this compound. Many researchers have also studied the impact of niobium additives,