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本文主要研究Zn对ZM6铸镁合金高温强化机理的影响。无Zn铸态ZM6合金晶界网状析出相为Mg_(12)Nd金属化合物;含Zn铸态合金晶界网状相为Mg_(12)(Nd0.70-0.85,Zn0.30-0.15)化合物固溶体。该相比化合物Mg_(12)Nd具有更高的热稳定性。固溶处理破坏了铸态合金的‘网状结构’,使大部分晶界网状化合物Mg_(12)Nd或Mg_(12)(Nd,Zn)能溶解到α-Mg固溶体中。因此该合金具有一定的固溶强化效果。时效处理能使α-Mg固溶体晶内析出大量的弥散沉淀相。无Zn合金的主要强化相为Mg_(12)Nd另外还有少量的α-Zr;含Zn合金的主要强化相为Mg_(12)(Nd,Zn),此外还有少量或微量的α-Zr、Mg_2Zn_3和ZrH_2等沉淀相。含Zn的ZM6铸镁合金的室温和高温强化机理都是固溶强化加弥散强化,而以弥散强化起主要作用。Zn对ZM6合金的高温强化机理是:当Zn溶入α-Mg和Mg_(12)Nd以后能够降低晶格自由能,同时提高合金α-Mg固溶体基体及其主要强化相Mg_(12)Nd的热稳定性。通过固溶时效处理,便可实现ZM6合金的高温强化。
This paper mainly studies Zn on ZM6 cast magnesium alloy high temperature strengthening mechanism. The Zn_ (12) Nd_ (8) (Nd0.70-0.85, Zn0.30-0.15) compounds were found in the as-cast Mg_ (12) Nd metal matrix and the Zn_ Solid solution. This compound has higher thermal stability than Mg 12 Nd. The solution treatment destroys the ’network structure’ of the as-cast alloy so that most of the grain boundary reticular compounds Mg 12 Nd or Mg 12 (Nd, Zn) can dissolve into the α-Mg solid solution. Therefore, the alloy has a certain solid solution strengthening effect. Aging treatment can make α-Mg solid solution precipitated a large number of precipitated crystal phase. The major strengthening phases of Zn-free alloys are Mg 12 Nd and a small amount of α-Zr. The main strengthening phases of Zn-containing alloys are Mg 12 (Nd, Zn) and a small amount of α-Zr , Mg 2 Zn 3 and ZrH 2 precipitates. The room-temperature and high-temperature strengthening mechanisms of Zn-containing ZM6 cast magnesium alloy are both solution strengthening and dispersion strengthening, while dispersion strengthening plays a major role. The mechanism of high-temperature strengthening of Zn on ZM6 alloy is that Zn can reduce the lattice free energy and increase the content of α-Mg solid solution matrix and its main strengthening phase, Mg 12 Nd, when it is dissolved into α-Mg and Mg 12 Nd, Thermal stability. By solution treatment aging, can be achieved ZM6 alloy high temperature strengthening.