Li Feiyin, Liu Sicong, Ma Shaojie, Zhang Xinping
School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
School of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
Materials (Basel). 2024 Nov 23;17(23):5738. doi: 10.3390/ma17235738.
Roll-bonding has rarely been applied to prepare rods for negative thermal expansion metamaterials (NTEMs). Parameters for quantitatively assessing the isotropy and cyclic thermal stability of the thermal expansion coefficient α of NTEMs are lacking. Here, the Ti-to-Al thickness ratio in bimetallic rods for "cross-shaped" node bending-dominated NTEMs was optimized using a general model proposed in the literature. The finite element method was used to determine the optimal initial thickness ratio of the billet, as well as the reduction ratio and rolling temperature. NTEMs were prepared with roll-bonded Ti/Al rods and Ti nodes. A relatively high thermal expansion coefficient was obtained when the thickness ratio of the 7075 Al alloy of the rods was in the range of 0.56-0.60. The optimized roll-bonding process to meet this thickness ratio was as follows: a rolling temperature of 400 °C, a reduction ratio of 50%, and TA1 Ti and 7075 Al billet thicknesses of 0.5 mm and 1.5 mm, respectively. The isotropy and cyclic thermal stability ratios were proposed to quantitatively assess the isotropy and cyclic thermal stability of the NTEMs. These results help to expand the preparation and evaluation methods for NTEMs.
轧制复合很少被用于制备负热膨胀超材料（NTEMs）的棒材。目前缺乏用于定量评估NTEMs热膨胀系数α的各向同性和循环热稳定性的参数。在此，利用文献中提出的通用模型，对用于“十字形”节点弯曲主导的NTEMs的双金属棒材中的钛与铝的厚度比进行了优化。采用有限元方法确定坯料的最佳初始厚度比、压下率和轧制温度。用轧制复合的钛/铝棒材和钛节点制备了NTEMs。当棒材中7075铝合金的厚度比在0.56 - 0.60范围内时，获得了相对较高的热膨胀系数。满足该厚度比的优化轧制复合工艺如下：轧制温度400℃，压下率50%，TA1钛和7075铝坯料厚度分别为0.5毫米和1.5毫米。提出了各向同性和循环热稳定性比来定量评估NTEMs的各向同性和循环热稳定性。这些结果有助于拓展NTEMs的制备和评估方法。
