为了进一步分析晶粒内部的针状第二相，采用了透射电镜对其进行了观察。图5

To further analyze the grain interior acicular second phase, using the TEM observation was carried out. Figure 5a along with a needle [110] zone axis α high resolution pictures can be seen a similar symmetrical arrangement twins. Figure 5b is a minimum unit of its cell, i.e., the minimum stacking unit. 14H can be clearly seen from the (0001) face of the stack close-packed way ABABCACACACBABA, wherein the structural unit comprises two ABCA arrangement, the two structural units was twinned symmetrical relationship with each other in FIG. 5b [8] . Notably, these same two stacking unit I2 and stack mode are stacking means comprising ABCA, with not the same, the former structure and composition order, a phase (i.e., long-period phase LPSO ), which occurs only Staggered structure, belonging to stacking faults.

In order to further analyze the second phase of the needle inside the grain, the transmission mirror was used to observe it. Figure 5a is a high-resolution photo of the needle-like phase along the axis of the alpha belt, which shows a symmetrical arrangement similar to that of a twin crystal. Figure 5b is one of its smallest cells, the smallest stacking unit. It can be clearly seen that 14H is stacked on the (0001) tight-tirate surface in a babCACACACBABA, which contains two ABCA-arranged structural units, which are twin-crystalsymmetric in Figure 5b. It is worth noting that the two palletizing units also contain THE same STACKING method of I2 with ABCA palletizing units, unlike the structure and composition of the former is orderly, is a phase (i.e., LPSO long cycle phase), the latter is only structural misalignment, belong to the stacking layer error.

In order to further analyze the acicular second phase in the grains, TEM was used to observe it. Fig. 5A is a high-resolution picture of the acicular phase along the axis of the [110] α band. It can be seen that there is a similar arrangement of twins. Fig. 5B shows one of its smallest cells, i.e. the smallest stacking unit. It can be seen from this that the stacking mode of 14h on the (0001) dense arrangement surface is ababcacacbaba, which contains two structural units arranged in ABCA, and the two structural units are in twin symmetry relationship with each other in Fig. 5B [8]. It is worth noting that the two stacking units also contain ABCA stacking units in the same way as I2. Unlike the former, the former is a phase (i.e. lpso long cycle phase) with orderly structure and composition, while the latter is only a stacking fault due to structural dislocation.<br>