论文部分内容阅读
The microstructure evolutions and mechanical properties of a heterogeneous Mg88Y8Zn4(in at.%) alloy during multi-pass equal channel angular pressing(ECAP) were systematically investigated in this work.The results show that four phases,i.e.α-Mg,18 R long period stacking ordered(LPSO) phase,Mg24Y5 and Y-rich phase,are present in cast alloy.During ECAP,dynamic recrystallization(DRX) occurs and the diameter of DRXedα-Mg grains decreases to 0.8 μm.Moreover,precipitation of lamellar 14 H LPSO structure is developed withinα-Mg phase.Both the refinement of α-Mg grains and precipitation of 14 H LPSO contribute to the increase in micro-hardness from 98 HV to 135 HV for α-Mg.In addition,a simplified model describing the evolution of 18 R LPSO phase is established,which illustrates that 18 R undergoes a four-step morphological evolution with increasing strains during ECAP,i.e.original lath → bent lath → cracked lath → smaller particles.Compression test results indicate that the alloy has been markedly strengthened after multi-pass ECAP,and the main reason for the significantly enhanced mechanical properties could be ascribed to the DRXed α-Mg grains,newly precipitated 14 H lamellas,18 R kinking and refined 18 R particles.
The microstructure evolutions and mechanical properties of a heterogeneous Mg88Y8Zn4 (in at.%) Alloy during multi-pass equal channel angular pressing (ECAP) were systematically investigated in this work.The results show that four phases, ieα-Mg, 18 R long The period stacking ordered (LPSO) phase, Mg24Y5 and Y-rich phase, are present in the cast alloy. During ECAP, dynamic recrystallization (DRX) occurs and the diameter of DRXedα-Mg grains decreases to 0.8 μm. LPSO structure is developed within α-Mg phase. Both the refinement of α-Mg grains and precipitation of 14 H LPSO contribute to the increase in micro-hardness from 98 HV to 135 HV for α-Mg. Addition, a simplified model describing the evolution of 18 R LPSO phase is established, which shows that 18 R undergoes a four-step morphological evolution with increasing λ during the period of ECAP, ieoriginal lath → bent lath → cracked lath → smaller particles. Compression test results indicate that the alloy h as been markedly strengthened after multi-pass ECAP, and the main reason for the significantly enhanced mechanical properties could be ascribed to the DRXed α-Mg grains, newly precipitated 14 H lamellas, 18 R kinking and refined 18 R particles.