Microstructure features and mechanical properties of non-heat treated HPDC Al9Si0.6Mn–TiB2 alloys
Chengyang Hu, Hongyi Zhu, Yihao Wang, Cunjuan Xia, Jiwei Geng, Dong Chen, Huawei Zhang, Mingliang Wang, Haowei Wang
Abstract
This study aimed to enhance the mechanical properties of high pressure die casting (HPDC) Al9Si0.6Mn alloys by incorporating in-situ TiB2 particles. The effects of TiB2 addition on the microstructure and mechanical properties of as-HPDC Al9Si0.6Mn alloys were investigated. The results showed that TiB2 addition refined the bimodal grain structure and eutectic Si morphology in the central region of the as-HPDC alloys, which was the primary contributor to the mechanical properties. The thickness of the skin region and band zone increased with increasing TiB2 addition, while the central region exhibited a reduced thickness but remained dominant on the entire cross-section. The optimal TiB2 content was found to be 1wt%, resulting in the 23.4% reduction in grain size and 10.7% enhancement in yield strength. The modified strengthening model based on the microstructure features of the central region accurately predicted the yield strengths of as-HPDC alloys. Finally, the morphological strengthening factors induced by TiB2 particles were analytically illustrated in the HPDC Al9Si0.6Mn-TiB2 alloys.