Abstract Ni-Mn-Ga single crystal material shows a strong magnetic shape memory (MSM) effect with reversible strains of up to 12%. Single crystal rods of up to 40 mm diameter are produced in Bridgman type processes. For actuator applications small sticks are cut out of the rods. The magneto-mechanical performance of these sticks depends among other parameters on their alignment with the crystal lattice. Thus, each inhomogeneity of lattice orientation within the rod reduces the achievable yield. The lattice orientation within the single crystal rods usually differs slightly between bottom and top region, and it shows local scattering due to misorientations between the growing dendrites. In the present study the macroscopic thermal stresses induced during the crystallization process are simulated. It is found that these stresses do not affect the crystal orientation. However, they may lead to shape changes of the single crystal rod.

中文翻译：

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Ni-Mn-Ga铁磁形状记忆合金单晶棒的热应力和局部结晶参数

摘要 Ni-Mn-Ga 单晶材料显示出强磁形状记忆 (MSM) 效应，可逆应变高达 12%。直径达 40 毫米的单晶棒采用 Bridgman 型工艺生产。对于执行器应用，从杆上切出小棒。这些棒的磁机械性能取决于它们与晶格对齐的其他参数。因此，棒内晶格取向的每个不均匀性都会降低可实现的产量。单晶棒内的晶格取向通常在底部和顶部区域之间略有不同，并且由于生长的枝晶之间的错误取向而显示出局部散射。在本研究中，模拟了结晶过程中引起的宏观热应力。发现这些应力不影响晶体取向。然而，它们可能导致单晶棒的形状变化。