Al_(67)Mn_8Ti_(24)Nb_1金属间化合物亚稳态粉末热压成形后的组织结构及性能

MICROSTRUCTURE AND PROPERTY OF Al_(67)Mn_8Ti_(24)Nb_1 INTERMETALLICS CONSOLIDATED WITH METASABLE POWDER

铸态复相Al67Mn8Ti24Nb1合金经10h高能球磨转变为弱有序的fcc结构，该正稳态粉末在热压成形过程中发生重有序化转变，恢复至复相结构．成形合金显微组织由Ll2基体和弥散分布的DO22结构Al3（Ti，Nb）第二相组成，第二相主要沿基体颗粒周围分布，一部分分布于基体内部，与铸态组织相比，成形合金晶粒明显细化,热压合金具有高的压缩强度，从室温至500℃基本稳定，高于500℃强度虽明显下降，但800℃时其屈服强度仍有531MPa，约为室温时的60％；成形合金室温压缩塑性为16．8％，退火后达20％，塑性随变形温度升高而提高，700℃以上试样受压时不断变形压扁。

After 10 h high energy ball mill, the dual-phase Al67Mn8Ti24Nb1 cast alloy changed into a weakly ordered fee structure. The ball milled metastable powder was consolidated by vacuum hot pressing. The microstructure of the hot-pressed A167Mn8Ti24Nb1 alloy consists of L12 matrix and DO22 Al3(Ti,Nb) second phase again. The grain size of the hot pressed alloy is much smaller than that of the cast alloy. The second phase distributed mainly around the grain boundary area, some of them inside the matrix. The temperature dependence of compressive properties of the hot-pressed alloy shows that the yield strength and ductility are rather stable until 500 ℃, but the compressive strength decreases and the ductility increases when the testing temperatuxe is above 500℃. The yield strength still remains 531 MPa at 800℃, about 60% of the room temperature value. When compressed at the temperature higher than 700 ℃, the samples could be continuously deformed without cracking.