A Critical Review of Mg–Zn–Y Series Alloys Containing I, W, and LPSO Phases

Abstract

Magnesium and its alloys are playing an increasingly important role in the transportation industry due to the pressing demand of lightweight structures to improve fuel efficiency and reduce CO 2 emissions. But the shortcomings of poor room temperature (RT) formability and high temperature strength, tension-compression asymmetry, and anisotropy are among the major issues which are currently limiting their widespread applications. Recently, research and development activities of Mg-Zn-Y series alloys have significantly increased because of their superior mechanical properties arising from the formation of different ternary phases known as I (Mg 3 YZn 6 ), W (Mg 3 Y 2 Zn 3 ), and LPSO (Mg 12 YZn). In this review article, the crystal structure of these phases and their orientation relationships with hexagonal magnesium matrix are discussed. Recent advances about I, W, and LPSO phase containing Mg alloys are presented, along with the effects of these phases on the microstructural evolution and mechanical properties including tensile, compressive, fatigue, and creep resistance. Important aspects involving thermal stability, phase transformation, and influence of heat treatment are also described. Based on the current status, some existing issues are pointed out and further studies are suggested so as to warrant safe and reliable lightweight structural applications of Mg-Zn-Y alloys in the automotive industry.

Effect of Ti and Zr Combined Modification on Microstructures and Mechanical Properties of Mg95Y2.5Zn2.5 Alloy Containing LPSO and W Phases

“…[5] The researchers have developed a series of Mg-Y-Zn alloys containing LPSO with high performance. [4,17] Although W and I phases can also reinforce the alloys, they are not as good as LPSO phase. In the lower Y containing Mg-Y-Zn alloys, the strengthening phases occur in the form of W and I phases.…”

“…[6][7][8][9][10][11][12][13][14][15][16] However, the large quantities of Y (>12 wt%) in the above alloys increases the cost of these Mg-Y-Zn alloys significantly, thus limiting their industrial applications. These three phases have strengthening effects in the following order: LPSO > I > W. [17] The thermal stability of phases follows the sequence: LPSO > W > I. [4,17] Although W and I phases can also reinforce the alloys, they are not as good as LPSO phase.…”

“…In the lower Y containing Mg-Y-Zn alloys, the strengthening phases occur in the form of W and I phases. [4,17] Although W and I phases can also reinforce the alloys, they are not as good as LPSO phase. These three phases have strengthening effects in the following order: LPSO > I > W. [17] The thermal stability of phases follows the sequence: LPSO > W > I.…”

“…[4,17] Although W and I phases can also reinforce the alloys, they are not as good as LPSO phase. These three phases have strengthening effects in the following order: LPSO > I > W. [17] The thermal stability of phases follows the sequence: LPSO > W > I. [17] It is clear that compared with W and I phases, LPSO phase is the best strengthening phase in Mg-Y-Zn alloys.…”

Sliding and Migration of Tilt Grain Boundaries in a Mg–Zn–Y Alloy

“…[1][2][3] But, Mg alloys usually exhibit poor ductility due to limited independent slip systems in hexagonal close packed structures at ambient temperature. [4] Moreover, cracks often occur in many Mg alloys during hot processing.…”