Hypoeutectic Al-7.6Si alloy has been developed with and without Al-5Ti-1B grain refiner through the gravity casting method. Effects of 2, 4, and 6 wt % master alloy (Al-5Ti-1B) addition on the microstructural morphology, mechanical properties (percentage elongation (%El) and ultimate tensile strength (UTS)), hardness and fracture behaviour of the Al-7.6Si alloy have been investigated. Unmodified hypoeutectic Al-7.6Si alloy consists of needle and rod-like eutectic Si ((Si)_E) particles with sharp corners inside the Al_α phase. In the grain refined Al-7.6Si alloy, TiB₂ is formed and these TiB₂ acts as a potential site for nucleation of Al_α grains. Therefore, the grain refined alloys have fine globular Al_α grains and fibrous (Si)_E phase. The bulk hardness, UTS and elongation (%) are increased in the grain refined alloys. Further, fractography show that the cleavage fracture is reduced in the modified alloy and fine dimple formation is increased.

中文翻译：

---

有和没有Al-5Ti-1B晶粒细化剂的亚共晶Al-7.6Si合金的结构性能相关性

通过重力铸造法开发了具有和不具有Al-5Ti-1B晶粒细化剂的亚共晶Al-7.6Si合金。添加2、4和6 wt％中间合金（Al-5Ti-1B）对Al的显微组织形态，力学性能（延伸率（％El）和极限拉伸强度（UTS）），硬度和断裂行为的影响已经研究了-7.6Si合金。未改性的亚共晶的Al-7.6Si合金由针和棒状共晶Si（（Si）构成_Ë）随Al内部尖角颗粒_α相。在精制的Al-7.6Si合金晶粒，的TiB ₂被形成，并且这些的TiB ₂作为用于铝的成核潜在位点_α晶粒。因此，晶粒细化的合金具有细小的球状铝_α晶粒和纤维状（Si）_E相。晶粒细化合金的整体硬度，UTS和伸长率（％）增加。进一步地，断层照相术表明，改性合金中的断裂断裂减少，并且微凹痕的形成增加。