Die-upset experiments on hot compacted commercial melt-spun powders MQP-A and MQP-B were carried out under an argon atmosphere at 500 to 800/spl deg/C with strain rates of 10/sup -4/ to 10/sup -1/ s/sup -1/. The kinetic analysis of the strain-rate stress relations yields the following dependences for the strain rate: (i) on flow stress, a power law with a stress exponent of 3, (ii) on temperature, a thermal activated process with activation energies of 280 and 400 kJ/mol for the MQP-A and -B samples, and (iii) on mean grain size, a reciprocal proportionality for MQP-A. These results indicate an interface-controlled solution precipitation process as the microstructural mechanism of hot deformation and texturing. Hereby the grain-boundary phase seems to be not required to be in the liquid state for deformation. Its presence is necessary for a crack-free deformation at high strain rates. In the case of radially textured ring magnets made by backward extrusion an area reduction of about 65% is necessary for optimization of the needed press stresses as well as the magnetic properties. Typical values are B/sub r/=1.25 T, /spl mu//sub 0/H/sub cj/=1.1 T and (BH)/sub max/=280 kJ/m/sup 3/.
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机译：对热压实的商用熔纺粉末MQP-A和MQP-B进行模锻实验是在氩气气氛下以500/800 / spl deg / C在10 / sup -4 /至10 / sup-的应变速率下进行的1 / s / sup -1 /。应变速率应力关系的动力学分析得出以下应变速率依赖性：（i）流动应力，应力指数为3的幂定律，（ii）温度，活化能为的热活化过程对于MQP-A和-B样品，分别为280和400 kJ / mol，以及（iii）平均晶粒尺寸，即MQP-A的倒数比例。这些结果表明界面控制的溶液沉淀过程是热变形和织构化的微观结构机理。因此似乎不需要晶界相处于液态以进行变形。它的存在对于高应变率下的无裂纹变形是必需的。在通过向后挤压制成的径向织构环形磁体的情况下，为了使所需的压应力以及磁性能最优化，需要减小约65％的面积。典型值为B / sub r / = 1.25 T，/ spl mu // sub 0 / H / sub cj / = 1.1 T和（BH）/ sub max / = 280 kJ / m / sup 3 /。
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