The influences of initial microstructures on the mechanical properties and the recrystallization texture of magnetostrictive 0.1 at% Nb C-doped Fe83 Ga17 alloys were investigated. The directionally solidified columnar...The influences of initial microstructures on the mechanical properties and the recrystallization texture of magnetostrictive 0.1 at% Nb C-doped Fe83 Ga17 alloys were investigated. The directionally solidified columnar-grained structure substantially enhanced the tensile elongation at intermediate temperatures by suppressing fracture along the transverse boundaries. Compared with tensile elongations of 1.0% at 300℃ and 12.0% at 500℃ of the hot-forged equiaxed-grained alloys, the columnar-grained alloys exhibited substantially increased tensile elongations of 21.6% at 300℃ and 46.6% at 500℃. In the slabs for rolling, the introduction of 〈001〉-oriented columnar grains also promotes the secondary recrystallization of Goss grains in the finally annealed sheets, resulting in an improvement of the saturation magnetostriction. For the columnar-grained specimens, the inhomogeneous microstructure and disadvantage in number and size of Goss grains are improved in the primarily annealed sheets, which is beneficial to the abnormal growth of Goss grains during the final annealing process.展开更多
采用数值计算和试验的方法,研究了直径30~50 mm Ti Al合金铸锭凝固组织的截面尺寸效应。结果表明:受径向散热和轴向散热竞争的影响,Ti Al合金铸锭的宏观组织存在竞争生长区、径向生长区和冒口影响区,随铸锭高径比增大,竞争生长区和冒口...采用数值计算和试验的方法,研究了直径30~50 mm Ti Al合金铸锭凝固组织的截面尺寸效应。结果表明:受径向散热和轴向散热竞争的影响,Ti Al合金铸锭的宏观组织存在竞争生长区、径向生长区和冒口影响区,随铸锭高径比增大,竞争生长区和冒口影响区占比减小,径向生长区占比增大。在径向生长区内,对于同一Ti Al合金铸锭,随散热距离的增加,柱状晶宽度增大,但增大的幅度逐渐减小;对于不同直径的Ti Al合金铸锭,在相同散热距离处,较大直径铸锭的柱状晶宽度更宽,且不同直径铸锭柱状晶宽度的差值随径向散热距离的增加而增大。通过拟合径向温度梯度和轴向温度梯度与铸锭直径和轴向散热距离的关系,建立了柱状晶生长方向与铸锭直径和轴向散热距离的关系。通过拟合温度梯度和凝固速率与铸锭直径和径向散热距离的关系,并耦合柱状晶宽度与温度梯度和凝固速率的关系,建立了柱状晶宽度与铸锭直径和径向散热距离的关系。展开更多
基金financially supported by the National Natural Science Foundation of China (No. 51501006)State Key Laboratory for Advanced Metals and Materials (No. 2017Z-11)+1 种基金the Fundamental Research Funds for the Central Universities (No. FRF-GF-17-B2)partly supported by a scholarship from the China Scholarship Council
文摘The influences of initial microstructures on the mechanical properties and the recrystallization texture of magnetostrictive 0.1 at% Nb C-doped Fe83 Ga17 alloys were investigated. The directionally solidified columnar-grained structure substantially enhanced the tensile elongation at intermediate temperatures by suppressing fracture along the transverse boundaries. Compared with tensile elongations of 1.0% at 300℃ and 12.0% at 500℃ of the hot-forged equiaxed-grained alloys, the columnar-grained alloys exhibited substantially increased tensile elongations of 21.6% at 300℃ and 46.6% at 500℃. In the slabs for rolling, the introduction of 〈001〉-oriented columnar grains also promotes the secondary recrystallization of Goss grains in the finally annealed sheets, resulting in an improvement of the saturation magnetostriction. For the columnar-grained specimens, the inhomogeneous microstructure and disadvantage in number and size of Goss grains are improved in the primarily annealed sheets, which is beneficial to the abnormal growth of Goss grains during the final annealing process.
文摘采用数值计算和试验的方法,研究了直径30~50 mm Ti Al合金铸锭凝固组织的截面尺寸效应。结果表明:受径向散热和轴向散热竞争的影响,Ti Al合金铸锭的宏观组织存在竞争生长区、径向生长区和冒口影响区,随铸锭高径比增大,竞争生长区和冒口影响区占比减小,径向生长区占比增大。在径向生长区内,对于同一Ti Al合金铸锭,随散热距离的增加,柱状晶宽度增大,但增大的幅度逐渐减小;对于不同直径的Ti Al合金铸锭,在相同散热距离处,较大直径铸锭的柱状晶宽度更宽,且不同直径铸锭柱状晶宽度的差值随径向散热距离的增加而增大。通过拟合径向温度梯度和轴向温度梯度与铸锭直径和轴向散热距离的关系,建立了柱状晶生长方向与铸锭直径和轴向散热距离的关系。通过拟合温度梯度和凝固速率与铸锭直径和径向散热距离的关系,并耦合柱状晶宽度与温度梯度和凝固速率的关系,建立了柱状晶宽度与铸锭直径和径向散热距离的关系。
基金support of the project from the National Natural Science Foundation of China (Grant No.50775112)the China Postdoctoral Science Foundation (No.20080430129)the National Key Technology R&D Program(No.2007BAE07B07)